OK, I've read all 10 pages and I don't think this has been asked...
If he can't get a job and you're willing to support him, why is he not at least doing this study FULL TIME to speed up this "bettering himself" (did I walk into a Dickensian novel btw?)
He absolutely should not be getting married.
He can't afford it. Whatever is paid for by other people, there MUST be some cost to him / you. The marriage licence cost would probably cover his bus fare for a year!
Yes, it's off if she reneged on a meet half way agreement. But he shouldn't have moved away. Yes, she did - but 10 miles. Not that far. He has chosen to move further, the distance that has made it unworkable.
You don't need a 2 bed place either. Sofa bed would do.
Getting qualifications is great. But it sounds like A levels which can be done in the evening. And as he doesn't even know what he wants to do - Counselling or teaching or youth work? - quite a wide range there - he should be studying something that will enable the next step when he does work out what he wants to do.
At this point, he may well be better off with an Access course.
Has he actually taken proper careers advice? He really really needs to.