You do one 65k transfer each calendar month. I've done it that way for years. It must show in your bank account as a foreign transfer. I use Wise to do the transfers
There's a number of factors to be considered. Have you already paid tax on the gain? Are you a UK tax resident? What does the UK DTA say about transfer of capital gain? My question is why would you transfer such a large sum of money to Thailand when you can get much higher return in the UK? I only transfer pension from Australia which is tax exempt, plus I also retain Australian Tax Residency and under the terms of the DTA, the Australian Tax Office has sole taxation rights.