I was really quite worried before we came to Thailand at the thought of two weeks gluten free, yeast free and onion free as these are used a great deal in Thai food. I really thought I would be very hungry all the time.
My husband was very organised and emailed all the hotels and any restaurants that we had booked from the UK. This turned out to be incredibly helpful. I still needed to go over everything with the waiting staff but they had at least some idea of what I was talking about. I also used my translation sheet to check about gluten free. Which has been helpful often getting thumbs up from the chefs.
We stayed at the Siam Kempinski in Bangkok which I would definitely recommend. Not cheap but staff very helpful and restaurant manager happy to help and keen to make my stay worry free.
I have eaten lots of fish so far, especially sea bass and have had far more spicy dishes than I expected.