I’m not putting out false hope, just because you don’t believe it. I reversed mine and I’ve had a normal A1C for 3 years, I know what the truth is. If you want to rename it “remission”, I don’t care, but mine is gone. Kaput. History. Never coming back because I’ll never stop eating this way.
Is it type 1 or type 2? If it’s type 2, it’s caused by poor diet and eating too many carbohydrates for your own personal physiology. You can totally reverse type 2 diabetes to a normal A1C (5.6 or less) with an ultra low carb diet. It might take 6 months or more depending on how high it is now, but may be a good way to go in the long run.
My wife has a Thai passport and a U.S. Passport. She arrives in Thailand and leaves Thailand on her Thai passport, and leaves the U.S. and arrives in the U.S. on her U.S. passport. No problems so far. Should be the same for the UK.
That money will have to sit in your Thai bank account for a minimum of 2 months before you can use it for your visa, which is why people normally get a non-O 90 day visa before they come so they have a solid month to get the bank account and money in it for it to season the following 2 months before their 90 days are up.