@Innes *****
There are plenty of Thai language schools where you can take language classes and get your visa that aren't universities or 4-year programs. I live on Koh Phangan (the next-door island) and we have two here. I'm sure there are plenty on Koh Samui as well.
I've heard of ED visas that go for 15 months (probably requires an extension and paperwork), the school should know all the details. If not, you could throw a tourist visa in there somewhere to fill it out till you hit 50.
I've found that when you make an effort to speak Thai and become part of the local community you can get things approved that aren't _technically_ the _official_ way of doing things.