UB - talk to the CAB, they will help you set up payments to various places if they can, and will help you with any debt management/financial management. They can also advise you on what money you might be entitled too.
I'm struggling to understand why your OH would be paying £200 a week for a BMW?!!! I mean, priorities..... Surely any car in working order would be better than a BMW that is forcing you into masses of debt??? I'd say sell the bloody car, pay the brother off and buy a very cheap run around!!!!! That is financial suicide!!!!
You're a better woman than me putting up with all that stress and drama. You'd be better off on your own in reality, he's dragging you right down!!! (Financially I mean!!). He'd be better off having his place of work as his main address and just visiting you. Whatever you do, do NOT declare that though if it's not the case. I've seen too many people do that and get all benefits stopped and investigated for fraud... Speak to the cab.