I don't mean to sound trite, but it's always darkest before the dawn. Try to prioritize. What is most important right now? Shelter, food, legal advice. Other things may have to wait. Is this month's mortgage paid? Is there food in the house? Yes? Good. That's 2 things you don't have to worry about today. One step at a time.
DO tell him you want money and how much you want. Tell him what you need per month to keep the house running and that's what you expect. He owes you, remember that. Yes, he may refuse, but at least you'll know where you stand.
Do you have joint banking? Do you have legal access? If so, go to the bank and withdraw half of what's there and open your own account. If that's legal to do in the UK, of course. At the very least, withdraw what you need for the next few days, if you can.
Apply for legal aid. And call the solicitor and just explain, maybe she'll work with you, maybe not.
Apply for any/all income assistance you may be eligible for. I don't know the ins & outs of the benefits system in the UK but it seems to me you are the what it was designed for. Someone who has suddenly had their financial support taken out from under them. Now is not a time to worry about being 'on benefits'. Now is the time to do what you have to.
As far as the car repairs, put that on the back burner for now, if possible, to worry about later. The sky bill? I think that's like our cable or satellite TV? Maybe you'll have to let that go for now, if you can. Again, prioritize.
Is it at all possible to work part time? I don't know how realistic that is for you, or if it's advisable. In the US it impacts the amount of support you receive.
I think I've seen people on MN advise people to call something called 'Women's Aid'? If it's like our US women's shelters they are invaluable in providing advice and referrals. And lean on friends or family, if you can. Talk to someone, don't isolate yourself. And don't be too proud to share your troubles with a friend or relative. You need emotional support almost as much as you need financial support.
You are NOT fucked, by any means. Yes, you are facing a rough time. But remember, now you have peace (or you will soon). Your home is now void of the turmoil he caused by just being there. Before the kids get up in the morning, feel the quiet. At night after they're in bed, sit for a bit and remember that you aren't sitting there wondering when he'll walk in, drunk or stinking of someone else's perfume. Your door is locked and your home is peaceful. Not worry-free, I know, but peaceful. And that peace will remain as long as you are strong and live one day at a time until this gets sorted. Give yourself some slack. You took the first step and got him out. "You done good" as we say here.