my accountant has overseas clients and I leave it up to him to deal with. He knows the rules and I won't worry about it. I will retain a UK address, banks and property too. UK Residency is an issue for those on pensions.
My accountant in UK said with dual taxation agreement, and UK tax paid would be offset in Thailand. But over 180 days resident in Thailand might make you non resident in uk. So ask an accountant.