Last updated: Wednesday 30 September 2026 (Europe/London).
Next update: when Smarty’s live 40GB affiliate voucher or giffgaff’s mid-data 5G goodybags change price or join windows.
By: Switch Editorial Team, Switch Squid Ltd
As of 30 September 2026, practical “5G SIM only deals” in the UK still mean mid-data plans on modern radio — and a live cash anchor is Smarty’s 40GB month-to-month plan at £7 on Three (£84 over 12 months if the promo holds), with giffgaff’s 25GB £6 rolling and 40GB £8 / 18-month plans as close O2-based alternatives. This guide ranks everyday 5G-capable SIMs for October shoppers who care about coverage and data-per-pound, not another Unlimited beauty contest. We may earn a commission if you buy through our links.
Sources: live Smarty and giffgaff affiliate destinations checked 30 September 2026 (Smarty 40GB voucher plan; giffgaff 25GB affiliate goodybag; giffgaff 40GB 18-month contract plan).
Smarty 40GB 5G-ready SIM — £7 / month-to-month
- £84 over 12 months at £7/mo if the live voucher price holds — subject to retailer terms
- 40GB UK data + unlimited UK calls & texts on Three
- Main limitation: promo voucher terms can change; confirm the retailer's plan page before you pay
- Month-to-month exit door — useful if coverage or usage may shift
Offer facts (checked 30 September 2026)
| Plan | Term | Promo price | Data | Network / 5G note |
|---|---|---|---|---|
| Smarty 40GB | Month-to-month | £7/mo | 40GB | Three radio — 5G where Three 5G and your handset allow |
| giffgaff 25GB | Monthly rolling | £6/mo | 25GB | O2 radio — affiliate goodybag terms |
| giffgaff 40GB | 18-month contract | £8/mo | 40GB | O2 radio — commitment; early-exit charges if you leave early |
| giffgaff Unlimited | 18-month contract | £14/mo | Unlimited UK data | Only if you truly burn past ~60GB |
“5G” on a plan label means you can use 5G where the host network has built it and your phone supports it. It is not a promise of Unlimited speed in every postcode. Run each retailer’s coverage checker for home, commute and workplace.
What “5G SIM only” should mean in October
Most people typing that phrase need maps, social video and moderate hotspotting on a phone that already speaks 5G — roughly 20–40GB — not a blank data cheque. Paying £14–£20 for Unlimited “for the 5G badge” is fine when Settings already shows 60GB+ months; it is expensive habit when you average 18GB on café Wi-Fi.
Illustrative Year-1 cash (promo prices, not quotes):
- Smarty 40GB £7 × 12 = £84
- giffgaff 25GB £6 × 12 = £72 (less data)
- giffgaff 40GB £8 × 12 = £96 during the 18-month term (£144 over 18 months)
- Unlimited £14 × 12 = £168 — outside the mid-data brief unless you need it
When Smarty 40GB £7 wins for 5G shoppers
Choose Smarty when Three coverage (including 5G where claimed) is solid, you want an easy exit, and 40GB matches real usage. At £7 it undercuts many 18-month mid-data contracts on pure monthly cash while keeping the cancellation door open for students, renters and anyone testing a new city signal.
Smarty 40GB £7 after the 5G coverage check
- £7/mo month-to-month on the live affiliate voucher
- Best when 40GB matches usage — not aspirational Unlimited
- Check Three 4G/5G coverage at every regular location first
When giffgaff 5G plans fit better
giffgaff 25GB £6: light users, strong O2 signal, happy on rolling top-ups.
giffgaff 40GB £8 / 18 months: stable O2 coverage and you will keep the line for the term.
Skip Unlimited for this brief unless Settings already proves you need it — then read our rolling-vs-18-month and giffgaff-vs-Smarty Unlimited guides instead.
Fit summary
Good for Smarty 40GB £7: Three coverage, mid-data habits, want month-to-month flexibility on a 5G handset.
Good for giffgaff 25GB £6: lighter data, prefer O2, want the lowest monthly cash.
Good for giffgaff 40GB £8: O2 homes willing to commit 18 months.
Not for: heavy hotspotters who routinely pass 60GB — budget for Unlimited instead.
Important conditions
- Affiliate voucher and goodybag prices can change — confirm the live retailer page the day you order.
- 5G availability is mast- and handset-specific; indoor 5G can drop to 4G.
- 18-month plans carry early-termination charges.
- Fair-use, roaming caps and tethering rules sit in each retailer’s terms.
- eSIM vs physical SIM: order early if you are travelling or changing handset the same week.
- Keep a PAC text (65075) ready if you are porting your number.
Switching steps
1) Check monthly data use in Settings for the last three months.
2) Confirm your handset is unlocked and 5G-capable if that matters to you.
3) Run Three (Smarty) and O2 (giffgaff) coverage for home and commute.
4) If 40GB and Three look right, order the live Smarty £7 plan via the tracked link.
5) Activate, confirm data with Wi-Fi off, then port your number if needed.
6) Diary any promo end dates so a price step-up does not surprise you.
Final decision card
Three coverage + mid-data 5G phone → Smarty 40GB £7.
O2 coverage + light data → giffgaff 25GB £6.
O2 coverage + stable 40GB need + can commit → giffgaff 40GB £8 / 18 months.
Heavy data → leave the mid-data aisle.
Smarty 40GB £7 — confirm the live voucher page
- Confirm the retailer's voucher page before you pay
- Activate inside any stated promo window
- Re-check Three signal if you move house mid-deal
5G myths that waste money
Myth 1: “I need Unlimited to use 5G.” False. 5G is a radio technology; your allowance still counts megabytes.
Myth 2: “5G always means faster downloads at home.” Indoor walls and mast load matter more than the logo.
Myth 3: “Any 5G phone automatically gets 5G on every MVNO.” The plan and host network must allow it, and the phone’s bands must match.
Worked examples
Renter on a 12-month tenancy: Smarty £7 keeps an exit door if you move to a Three-weak postcode later.
Parent buying a teen line: 25GB £6 often covers school Wi-Fi habits; upsize only if gaming hotspotting appears in the bill.
Commuter who maps offline areas: 40GB is the safer mid-data bucket; Unlimited only if tethered laptop days are routine.
Related SwitchSquid SIM guides
For cash under £10 see that October twin. For Unlimited term maths see rolling vs 18-month. For brand Unlimited detail see giffgaff vs Smarty Unlimited. For household multi-line sizing see family SIM sharing. This URL stays on 5G-capable mid-data deals.
Roaming and EU trips on a £7–£8 plan
UK mid-data plans are priced for domestic use. Roaming allowances are smaller than marketing memory suggests. For a two-week holiday, a temporary travel eSIM can be cheaper than upsizing to Unlimited at home “just in case”.
How to size 25GB versus 40GB without guessing
Open your phone’s data usage screen and look at the last full billing month, not a quiet week on holiday Wi-Fi. Add a buffer of about 20% if you expect a new commute. If three recent months average 12–18GB, a 25GB £6 goodybag is usually enough. If you sit at 28–35GB, Smarty’s 40GB £7 (or giffgaff’s 40GB £8) is the calmer 5G-ready choice.
Hotspotting is the silent budget killer. A single evening of tethering a laptop for updates can burn 5–10GB. If that is weekly behaviour, stop pretending mid-data will hold.
Handset compatibility still matters. A network-locked phone will not thank you for a perfect £7 plan. Unlock first. eSIM-capable phones can activate faster when a promo window is tight.
Credit checks, top-ups and bill-payer hygiene
Month-to-month value SIMs are often lighter on credit checks than 24-month handset contracts, but checkout prompts vary. Top-up brands need a funding method you will actually remember. Parents paying for a teen line should decide whether the account sits under the teen’s login or a parent email. Diary the first renewal so a promo step-up does not become a surprise Direct Debit.
If you port a number, activate the new SIM first, confirm data with Wi-Fi off, then send the PAC. Porting into a dead SIM is how people lose a day of service on a Monday morning commute.
FAQ
What are the best 5G SIM only deals in October 2026?
Among live affiliate plans we checked, Smarty’s 40GB at £7 is a strong mid-data anchor on Three, while giffgaff’s 25GB £6 and 40GB £8 cover O2 households. Confirm live pages before you buy.
Is Smarty 40GB still £7?
The affiliate voucher destination checked on 30 September 2026 showed the £7 mid-data plan. Prices can change — verify at checkout.
Does a 5G SIM guarantee 5G everywhere?
No. You need network 5G coverage, a compatible handset and plan permission.
Which network is Smarty on?
Smarty uses the Three network. giffgaff uses O2.
Can I keep my number on a £7 SIM?
Yes. Text PAC to 65075 from your current provider and port after the new SIM is active.
Should I buy Unlimited instead?
Only if you regularly need more than about 40–60GB. Otherwise mid-data is usually enough.
Do affiliate exclusive goodybags last forever?
No. Join windows and campaign codes can close. Order while the live page still shows the price you expect.
Do you earn commission?
Yes. SwitchSquid may earn a commission at no extra cost to you when you buy through the tracked retailer links on this page.
