I've used Brett's courses, and they're worth it. He emphasizes learning to read Thai which is important if you want to learn to pronounce Thai correctly. His site is
it is the only Thai Embassy in Berlin. I applied for a 30 day tourist visa, which ironically I forgot to check on the form the first time I handed it in. I’ve found the posts in this group useful and thought I’d try to contribute, sorry if I missed anything else.