you are correct, and I am sure it isn't a problem. I just find it hypocritical for a Bank to tell you to lie about the purpose of a transaction one day and then demand all sorts of paperwork to prove you are telling the truth about a transaction the next
that is also what Wise say, of course the Bank may do this or they may not, they will certainly charge you and take up hours of your time. Not exactly the 'convenient cost effective' option that Wise say they are...
Good luck, 59 is a good age in life to make a new move. Thailand can be as expensive or as cheap as you want it to be. Also, as in most countries it also depends where you live and the associated lifestyle; if you just want to chill in rural Issan you will be relatively well off, in the posh parts of Bangkok you will struggle to have any quality of big city life.
I would ensure that you spend 181 days in the UK to remain a resident and ensure your pension is not frozen and a maximum of 179 days in Thailand to ensure you are not tax resident in Thailand. 6 month Multiple entry visa is your friend