@Ben ****
, you need to be contacting the SCHOOL you're going to enroll in before you wing your way here on a tourist visa to make sure they can indeed get the in country Non-ED visa.
Unfortunately this is a VISA advice group, not a what school can I go to.
Post on a f/b page related to where you're going to live in thailand and ask your questions about language schools there. You'll get answers for sure