London to Chiang Mai (LHR–CNX) — Airlines, Schedules & Connections

British passport holders enter Thailand visa-free for up to 60 days (extended from the previous 30-day allowance). No fee, no advance application. Passport must be valid for at least 6 months beyond the date of entry. A single 30-day extension is available at any Thai immigration office for THB 1,900 (about $53), giving a total possible stay of 90 days.

You need proof of onward travel (airline ticket out of Thailand within 60 days). Immigration can ask for proof of sufficient funds: THB 20,000 (about $560) in cash or equivalent per person, or THB 40,000 per family. This is rarely checked but enforced sporadically, especially at land borders. For longer stays, apply for a 60-day Single Entry Tourist Visa at the Thai embassy in London for GBP 30, or a Multiple Entry Tourist Visa for GBP 150 (valid 6 months, 60 days per entry).

Direct flights from London Heathrow to Bangkok (BKK) run about 11 hours 30 minutes on Thai Airways and British Airways. The Thai baht (THB) trades at roughly 35.5 THB per $1. No vaccination requirements for UK arrivals, though hepatitis A and typhoid are recommended. Bangkok has two airports: Suvarnabhumi (BKK) handles most international flights, Don Mueang (DMK) handles budget carriers. Transfer between them takes 45 to 90 minutes by taxi or shuttle bus.

Heathrow Express runs from London Paddington to T5 and T2/T3 in 15–21 minutes (£37 single, cheaper booked online or via the Heathrow app). Elizabeth line (Crossrail) is a lower-cost alternative; Paddington to T5 in 34 minutes from £13.50 with an Oyster/contactless cap of £14.90. The Elizabeth line also serves central London stations including Bond Street, Farringdon, and Liverpool Street.London Underground Piccadilly line serves all terminals (T2/T3/T4/T5) from central London in 40–60 minutes (£6 with Oyster). Taxis (black cabs) from central London cost £55–90 depending on traffic. Coach services from Victoria Coach Station (National Express) cost from £10 booked in advance.