At this time of year the air is pretty awful all over the region, but other than this brief period Phuket / Krabi / Phang Nga have very clean air and a temperate climate year round.
I don’t think you need to worry about being taxed on your pension in Thailand - not a tax lawyer but that seems to be the consensus.
Farang bashing in the media is a current fad - will pass and return from time to time, but doesn’t affect daily life.
Immigration is straightforward if you understand and follow the rules.
In short, I think your’re worrying about nothing much
As you grow older your health insurance premiums will rise - decent inpatient cover for a 50 year old will cost THB70k a year and will steadily rise year on year.
As most people have stated there is a huge range of standards and costs of living here.
GBP200k is about THB9m - in popular expat areas such as Phuket / Samui / Hua Hin that will buy you a house or decent condo and a new / near new car without any / much change.
GBP1600 is about THB70k per month. Say 10k for health and 15k per week for everything else. Depends what you like doing: a nice meal with wine can cost 2k-3k, a round of golf 2k-5k, a night in a cheap beer bar with food maybe 1k. A massage 300-700, an afternoon at the beach 500, an afternoon / evening at a beach club 3-5k, the list goes on.
So in summary I agree with you, the GBP200k/1,600 per month is a bit tight. Double that and you’re very comfortable, triple that and you’ll have a fantastic life
My guess is (like me) a year in Bangkok will have you craving greenery, clean air and fresh breezes. Try it, enjoy it, but suggest don’t make any commitments beyond a 12 month lease.
After that year you’ll either be head over heels in love with the city and its quirks, or be ready to look elsewhere
I think that’s a very bleak outlook for this beautiful island: yes there are Russians who have settled here, and the ones I have got to know are great people, who speak great English, are well educated, and enjoy a drink. Lots of development underway, and some new roads which we hope will compensate. There are still large areas that are underpopulated, lots of protected national parks and deserted beaches if that’s what you’re seeking. I think those who criticise Phuket don’t know it too well