The airfield refered to in the posts above is the Royal Thai Flying Club at Bang Phra.
It has recently recruited instructors after a period of no training.
It is possible to validate a foreign licence but it is a long drawn out procedure that takes several months. Once validated the licence only allows flying from the club cited in the paperwork. Flying from any other location requires a new permit.
With a military junta having ruled for several years things are unlikely to change in the near future.
Details here.
HOW TO VALIDATE YOUR FOREIGN LICENSE TO FLY IN THAILAND -- www.thaiflyingclub.com