hi AG,
from what little I know of how the system works - (and I think it was you asking about HB as well??) you'd not get HB on any rent as althou you are a lone parent with that level of equity sat in the bank they would make you use this first before the offered you some help - right or wrong it's not fair but I THINK that's how they work things - but can ask SIL later on if you like (it's what she does).
re the CAB - I honestly can't beleive CAB would tell your XH that he doesn't have to provide a roof for your children. either way his debts - are his problem he has to provide for his children which in my mind incl's a house.
ishe - weren't you looking into a claus where you couldn't sell the house until the children were 18?? would it apply here.
also look into seeing if you can buy your X out of the house - if you can't afford it yourself, can you have help from parents/family members so they also own a share of the house?
in our area council waiting lists are 2 years, and the hard fact is there's not enough of those either (in my area anyhow) - not 2/3 beds - over 60's yes! (typical! lol) any how, also my council won't help until the last minute - as in you have a court evictions - as told to me by the lady when I took my forms in - her words were 'don't bother coming to us until you have an eviction notice from the courts ' followed by get a private rented house and get your parents to pay for it anyhow.
important things to do today :-
see a solicitor of your own - take a pad, write down all questions you want answered now while you think of them, and write down all answers. better to know your rights and not use them that not know them and need them. Yes your X has a baby on the way - but you have 2 children (i'm assuming both his) to providse for.
second thing, why does your DS want to live with his dad? i'd be reluctant to let him go there esp as GF is due to have the baby next month - I imagine your DS will be wanting a lot of attention from his dad and to feel secure - a baby will unbalance this. so suggest to him we give it 6 months to settle down etc and then if he still wants to live with his dad he can possibly? you know your kids best but is splitting them up the way to go? your X could possibly say if he doesn't pay you anything for your DD you won't have to pay him anything for your DS, (not sure if it would work that way but possibly as then that would be one less thing for him to 'pay out' if he's got the new baby)
anyhow not sure i've been much help, but I really strongly advise you find out all you can today about everything - the kids, benifits, the housing etc etc, and see what you can do. also as itis says you don't know until you try so anything is worht trying.
DON'T BE FORCED INTO SELLING UNTIL YOU KNOW YOUR RIGHTS.
I know you do regret splitting from your H but that's no reason to let him have everything his own way (if only I could take my own advice on that front! lol)