Rough google translation

Bangkok bank, are able to issue a letter confirming the FTT status

I know the UK Embassy requires an online appointment, often booked up weeks in advance. I would imagine other Embassys are similar...

No need for a tourist visa, especially with the bank account already opened. Arrive on the 30 day visa exemption and get your application in the following week.

Note when you leave the UK, your airline may want to see a ticket out of Thailand within days, before allowing you to board. A cheap refundable ticket out of Thailand (not home) is all you'll need, cancel that and get a refund after arrival.

@James *******

thanks, edited for clarity.

yes, doing it this way helps get's over the challenge of opening a bank account in Thailand on a tourist visa or visa exempt entry stamp, which is getting increasing difficult and much easier on a non-imm visa.

If the non-imm o visa.

It depends which immigration office you will be using, with regard to specifics on the seasoning of the money. E.g. some require 2 months seasoning before the 90 day visa application, others require it seasoned for two months before 12 month extension to the 90 day.

I think you have your wires crossed...

Do you mean the non-imm oa visa, which you get at home?

Or

Do you mean the non-imm o visa which you normally get once in Thailand?

Note the big differences between a non-oa acquired from outside Thailand, to a non-o acquired IN Thailand.

Non-oa, can use home money but requires ongoing insurance mandatory insurance.

Non-o (in Thailand) you need to have banked 800k in Thailand, then 1900THB per year after the initial 90 day @ 2000THB, with no mandatory insurance.

Mandatory insurance can get very expensive, depending on age, health etc...