Hecate I think my own experience has coloured my opinion somewhat.
I waited on a social housing waiting list for a very long time to be offered my HA house. I love my house, it's in a lovely area, I moved in when my eldest was 2.5yrs old, and I was single until I met my XP when my eldest was 13.5yrs old.
After 4.5 years of abuse, I had had enough, XP had been abusive on every level, and throughout the whole time he was living at mine, he had gambled away most of his earnings, claiming he hadn't been paid (admitted this later but I long suspected with no proof). I worked my socks off to pay for everything, while XP ran up debts left right and centre. He ran up an £800 phone bill over one weekend I was working, and that's just one example.
He didn't pay for very much at all. I almost lost my home, because stupidly I trusted him to pay the rent at the PO up the road, and unbeknown to me, until the landlord wrote 3 months later
XP had pocketed every penny.
He had no rights to remain in my home, he was there purely as an 'invitation to stay' and when I attempted to revoke that invitation, the police told me that he was as entitled to live there as I was because he had already been there for 2+ years. 
I took the police at their word and XP refused to move out.
It took a long time to get him out, and I was left with a postponement of possession order on my home, and at least £11000 of debt.
He had nowhere else to go unsurprisingly and I even had his family telling me a load of bollocks that XP was perfectly entitled to evict me from my home and live there himself, whilst keeping all the bills in my name, so I'd have to continue paying for everything while he sat pretty in my home and that was what they believed he should do if I were to insist on throwing him out.
There was no way on Gods green earth I was going to go and leave my home, which when I moved in, XP had only just started secondary school, when it is my tenancy and legally he had no right to live here without my permission anyway.
Been free of XP for 2 years now, and am glad I stayed in my home.
XP is now living with another g/f who thinks he is Mr wonderful. 
Sorry for the long post, but each situation needs to be judged on its individual merits (not saying you wouldn't judge individually, just making the point for the sake of it
), I was perfectly entitled to escape the abuse and retain my home and I did, but I agree that it is far more complicated for many other people.