Baht in the pocket, data on the phone, a card that actually works in a mall. That is the unglamorous layer. Get it wrong and every other page on this cluster — parks, wats, 7-Eleven rice boxes — becomes a mime show. Get it right in arrivals and you can ignore it until the next ATM.
Currency, then the phone
Thai baht (฿ / THB). Notes: 20, 50, 100, 500, 1,000. Coins vanish in a taxi. Keep small notes for stalls, temple boxes, and the park gate that has never seen contactless. Land & Sea’s park fees are still a cash culture: Khao Yai foreigner adult 400 THB, Doi Inthanon 300, Similan park often bundled around ~500. Do not arrive at Pak Chong with a card and a smile.
ATMs at BKK, DMK, and most 7-Elevens take UK debit cards. Expect a foreign-ATM fee on the Thai side plus whatever your UK bank adds. Withdraw larger amounts less often — the Thai fee is per dip, not per baht. Cover the keypad. Ignore anyone who “helps” at the machine. If the ATM eats the card, stay with the machine and call the number on it; do not follow a stranger to a back office.
Cards. Visa and Mastercard in malls, hotels, Grab, and many restaurants. Street food is cash. Contactless is common in Bangkok, patchy on islands, rare at a national-park booth. Tell the UK bank you are travelling or the first hotel hold will look like fraud.
PromptPay is everywhere for locals: a phone number or national ID as a payment address, QR on every stall. It is not a tourist tool. You need a Thai bank account to sit on the end of it. Do not stand in a night-market queue waving a UK banking app at a PromptPay QR and then looking betrayed. Cash, or a stall that actually takes Visa.
Airport Wi-Fi is for the first message home. It is not a week of maps. Buy the SIM or eSIM before you leave arrivals if you can face the kiosk; otherwise the first 7-Eleven or an AIS / True shop on day one. A UK Type G plug will not love a Thai socket. Thailand is Type O (and you will also meet Type A/B/C in older buildings). A compact travel adapter belongs in the personal-item bag, not the hold.
AIS, True, dtac — pick a network, not a slogan
The three names on the kiosk are AIS, True (TrueMove H), and dtac. Coverage is good in cities and on the main islands; it is merely fine in a karst pocket or a park valley. Tourist desks sell tourist SIMs and will put an eSIM on an unlocked phone. Bring the passport; they will scan it because the regulator wants a name on the number.
We are not going to invent a fake “299 THB / 15-day” SKU that was true for one kiosk in 2024. Tourist eSIM and tourist SIM packs in 2026 typically buy you on the order of 8–15 days of data for hundreds of baht, not thousands. Exact gigabytes, validity, and whether calls are included change by kiosk and week. Read the board. Ask them to show the validity date on the receipt. If the price is an outlier in either direction, walk to the next counter.
| What you buy | Typical shape (2026) | Verify at the kiosk | Notes |
|---|---|---|---|
| Airport tourist SIM (AIS / True / dtac) | Physical nano-SIM, passport scan, staff insert it | Days of data, GB cap, whether hotspots eat the cap | Easiest when you are wrecked; not always the cheapest |
| Airport / city eSIM | QR, unlocked phone, same three networks | Phone is actually unlocked; QR works before you leave Wi-Fi | Keep the UK SIM or eSIM for bank texts |
| 7-Eleven / shop top-up | Cash or card onto a number you already have | The correct network logo on the card | Staff will do it; say the phone number slowly |
| Tourist pack on Sukhumvit / old town | Same 8–15 day idea, hundreds of baht | Validity printed, not just spoken | Compare two shops if you have the energy |
| UK roaming | Daily cap from your UK provider | Whether Thailand is in the “included” list | Fine for a 48-hour transit; expensive as a fortnight |
Top-up after that is a 7-Eleven muscle memory: point at the network, say the number, pay, wait for the SMS. You do not need a Thai bank account. You do need to know whether you are on AIS, True, or dtac — the logos are not interchangeable.
Keep the UK number reachable on Wi-Fi (iMessage, WhatsApp, or a dual-SIM / eSIM slot) for bank texts and the one SMS that never routes through a Thai number. Turn on a travel notice with the bank anyway.
Cash versus card versus “I will just use Grab”
Cash for: street stalls, many wats, DNP gates, some taxis that are not Grab, village 7-Elevens when the machine is “broken”, tips that are actually a round-up.
Card for: hotels, malls, BTS/MRT top-up machines that take them, nicer restaurants, Grab (in-app).
Grab is the foreigner-legible taxi. It is not a bank. It still wants a card or cash-out option that works. Pin the pin; do not argue the route at the first light — that social register is Kreng jai and Etiquette.
BTS and MRT are the reason you should not take Grab across central Bangkok at 18:00. A stored-value card or the app saves twenty minutes of queue theatre. First-week sequence: First week.
Airport ATMs are fine. The rate is the rate. Money-changers in arrivals are not automatically a trap; they are also not automatically better than your UK bank’s ATM rate. Do not change a trip’s worth of cash at Heathrow as a personality.
Alcohol, 7-Eleven, and the hours that are not a conspiracy
Beer in 7-Eleven follows sale windows: 11:00–14:00 and 17:00–midnight, and no on major Buddhist holy days (Makha Bucha, Visakha Bucha, Asarnha Bucha, Khao Phansa, Ok Phansa). Staff will refuse. That is the law, not kreng jai. Drinks pillar: Thai Beer & Spirits. Rice boxes when the beer fridge is locked: 7-Eleven meals.
You do not need PromptPay to eat. You need 45–69 THB in coins and notes for a rice box, or 15–30 THB for Mama. That is Table & Bazaar’s beat; this page only exists so you can pay.
Apps worth having before wheels-down
Grab. Maps that work offline for the first hotel pin. A translation camera for menus. The bank app with travel notice on. An airline app that actually shows BKK versus DMK — they are not interchangeable; First week will shout this again.
Entry is a separate stack: TDAC, 60-day visa exemption still being stamped for UK passports as of August 2026, passport six months and a blank page. Visa & entry. Do not mix up a SIM kiosk with immigration. One wants a passport scan for a phone number. The other wants you out of the hall.
Once the SIM lights up and the first 1,000-baht notes are in a split pocket, the boring layer is done. Spend the attention on the wat dress code and which coast you actually booked.