If you don't mind flying to London then I think Thai are you best bet for a non-stop flight. Eva Air also do a non-stop flight, friends have recommended them to me but I've yet to fly with them. For a direct one stop flight Etihad are pretty good, you would have a stop in Abu Dhabi, a lot of people who use them rate them better than Emirates, I'm not sure if they use any other UK Airports though.

We've flown both non-stop and via the middle east to Thailand and now prefer to take that short break in the middle-east, as it seems to reduce the affect of jet lag, and the fear of DVT. Just come back from Thailand and we used Etihad as they came out cheapest and we'ed used them before and quite frankly they've become our airline of choice as we have enjoyed the flights with them....good food, allocated seats, good inflight entertainment, comfy modern fleet and they gave us a 30kg hold luggage allowance in economy.

There are numerous options these days for flying to the far east. You should consider what is important to you - would you like a stop over somewhere else for a day or two before moving on to Bangkok? Do you prefer just a flight that offers same day (sometimes quick sometimes long connections). Do you want to arrive at Bangkok quickly?

From Scotland yes you can use Emirates via Dubai or consider BA via Heathrow and their partners (also British Midland with their partners) or consider KLM /Air FRANCE via Amsterdam/Paris.

You may well find routing via Heathrow and then via another destination works out a bit cheaper than flying direct to Bangkok from Heathrow but the time involved may not always suite.

Nivsy

To be honest I would have thought the Emirates from Glasgow option might be the best, some of the connecting times are only a few hours, so maybe quicker than flying down to Heathrow and catching non-stop flight from there. Another option we've used in the past is flying from local airport to Schipol then non-stop to Bangkok on China Airlines (a Taiwanese airline). If you're going straight to Hua Hin rather than staying in Bangkok then you have a lengthy land transfer at the Thailand end as well to take into account.