yes, I am self employed in the uk, it fell under doing a self assessment tax return fortunately. I applied literally a week after it started in July, not sure if they've tweeked it a bit now but I'm good till July 2029 😁
I am also having problems where to apply for any visa. The Thai Embassy website has no links. I'm planning to go in 3 week till April and want to do the stv I've seen mentioned by at a complete loss of where to start!