It would be nice, but it isn’t completely necessary. Take out 20k 2 times per month cash, you’ll pay around £12 for that, the rest you can do on card or wire transfer. I haven’t tried it yet, but the qr code thing from true money sounds decent. At the end of the day it’s cheaper here compared to where I’m from, so I don’t really fuss to much on a little atm tax, whatever.
You should be fine, I made a little portfolio on canva, showing images of what I do, as well as screen grabs of incoming payments and monthly takings etc.
and I wrote a cover letter myself, explaining my business and clearly stating I wouldn’t conduct my business in person in Thailand, or with Thai customers in Thailand. I think they like it if you reiterate that you’re not going to do anything they don’t want you to do there. London embassy was super quick and easy to deal with for me