I'm planning a trip to the UK at Xmas as it's the only time I can use my BA voucher. 

Does anyone know if it possible for my kids who are dual citizens(Thai/British) to go and come back here  without any hassle?

The school year is very intensive this year and I don't want to keep them out too long. Actually, I'm hoping to be a Thai citizen myself by the end of the year. 

 

Nobody knows what's going to happen down the road, if it was me I wouldn't take the chance just to use a ticket. Could be a non issue (doubtful) or it could be a travelers nightmare, I would have to have a extremely important reason to leave. Good luck.