OP, you say you are still planning the wedding, and how to afford it. In your financial situation, I think you should concentrate on the getting married part, not the wedding itself. You can get married very very cheaply and do not need to have a wedding. Since you can then live together, and you say that will improve your financial situation, it might help with your other financially related problems. You also need to get the accomodation situtation remedied as soon as possible - there is no point in talking about having those children live with their father full time if you don't have adequate accomodation for them. Take care of the practicalities first.
Very good advice. The housing is in the works- if my older son moves out, we can all fit into my current apartment, a 3 bedroom. If my older son chooses to stay at home, in my building (actually, it's 6 buildings part of the same community), I can apply for a larger apartment, 4 bedroom, which would fit out needs, and the waiting list is 2-4 months. My older son just turned 18 yesterday and has not yet decided if he's ready to move out.
I agree on the wedding verses marriage. Personally, I'd prefer a small wedding, sweet but inexpensive. My fiance prefers a large wedding, inviting just about everyone he's ever met. We've compromised, it's only about 65 people, family and close friends, but we're gonna have to tweak it some more. We both agree that we can't start out our marriage broke, or at lease, any broker than we already are.