maybe think about the new tax rules and not just send your income to Thailand. If you financially can, keep you income going into your own countries bank account and transfer drawdown money from previous savings. That way you won’t have to pay Thailand tax
Twice traveled on a one way ticket Heathrow to BKK . Never thought anything about it being a problem. Not questioned about it so happy days. Thai airways. Booked a single flight back to LHR from Thailand when time suited .