As long as she withdraws max amount of 30,000 baht the 220 baht fee is not much. Withdrawing 1000 baht being charged a fee of 220 however is extortionate at 22%. She will be able to get a local bank account once she has long term ED visa; Bangkok bank and Kasikorn easiest. Thai QR is absolutely essential.
Closing UK accounts would be a mistake unless the banks de-bank you. The 800,000 baht must be deposited on a Thai account to qualify for (first) annual visa extension.
“my wife will be with me” will help greatly with budgeting; single men get bankrupted in girlie bars. I would agree with others that 65,000 baht is a sensible budget (or anything between 40-80k). When considering CM do pay a great attention to agricultural burning season as you may need to have extended holidays in the south between February and April due to the smoke. It has been bad … very bad in recent years (anywhere BKK and north of BKK…. It is real health hazard and even civil servants were asked to work from home last February and March).