You also living in a fantasy world if you think that there is any way to transfer funds to Thailand for free. The best you can hope for is a bank in the UK that will reimburse you for the ATM fee that all Thai banks charge. And even if you do find a bank in the UK that does provide free Swift transfers you are still going to get hit with a fee the transfer on the Thai end

One of my UK banks does indeed send GBP to me here via SWIFT for free. I didnt believe it either when I first read it, and I emailed them to get confirmation! It's a perk of having a high interest account with a healthy balance. I just pay the incoming 0.25% fee (capped at 500B) that is common with Thai banks, and of course the Thai bank takes its (negotiable) spread on the exchange rate.

^ yes I believe I have seen citibank 'citigold' account holders get a free allowance of like 8 swift for each month.

Quite a few options for almost free too if hunt about, I have flexplus at half the monthly cost (£5) that gives me no load & no cut on exchange rate and it done at the stated visa rates that can be checked daily online & are better than thai banks marginally so the casual use for smaller amount via atm wherever I am is simple & good value. account has couple other perks that maybe useful to some, also has 3% AER on the current account on 2,500GBP so that earning covers my monthly fee. Another one for possible free foreign debit card use is Norwich & Peterborough BS Gold Classic account if can meet monthly payment or hold balance over 5,000GBP.