I sold my house in Australia, bought a condo in Thailand. I don't understand why the OP can't maintain a bank account in the UK. I have one in Australia, plus investments. The last time I visited the bank ( actually a credit union ) was over 10 years ago, everything is done by internet and phone. I have two Australian debit cards for use in emergency.
My will ( Thai and Australian ) states my assets in Australia are to go to my son there, my assets in Thailand go to my Thai GF.
I found selling the house freed up a lot of capital, cut rates and insurance to zero, and I no longer had maintenance to concern me.
It would be prudent to set up a joint account with your Thai partner, with sufficient funds for her to live on, while probate is settled in both countries. I understand Thai probate takes about 6 months. My GF has enough funds for 18 months in our joint account.