On average, Bangkok (BKK) is the cheapest airport for flying into Thailand, so consider starting your trip from there. 20 direct and indirect flights land in the country from the UK every week so, if you can’t find what you’re looking for, try searching by month to see a broader range of flights. Searching by month will also show you the cheapest day to fly.
You might like to know that, out of all three airlines that fly to Thailand, SriLankan Airlines usually has the lowest prices. What are you waiting for?