Hopefully everything will be open tomorrow for you to get some good legal advice, although I suspect citizens advice might not reopen till Monday.
He's probably had a good six months of thinking time to sort out in his head what he wants to do, where he wants to be and like Vivacia I always think...cherchez la femme!
My ex when he finally let kept up the bills but then began torturing me by slowly cutting them off one by one without warning.
So, just a word of warning, even the most amicable of splits and ours wasn't can start nice and turn ugly so get advice for you.
As a previous poster mentioned you will have four mouths to feed so you need everything you are entitled to . You can't trust your husband to play nice. It's the old survival instinct kicking in.
I'm glad you are so strong and positive but do expect a few wobbles when he goes. Even if the marriage has run its course there will still be sadness that it didn't fulfill it's earlier promise. So do look out for that. Mum had a friend who gave us the impression she was only tolerating her second husband. She talked of leaving him often, slept on the sofa when they had a row, yet carried on something terrible when he died and how she hated his empty side of the bed. I had to give my head a shake, i really did.
Good luck to you and I hope the split stays amicable and you come off better than expected.