Hi
I give legal advice on this sort of thing, so I'll try. First of all, where are you going to live? If you want to stay in your house then you probably can as you have the children, if your husband resists then you can ask a solicitor to apply for an occupation order, even if the house is in his name only. You can get legal aid for this.
You would be able to get some help from the DWP for the mortgage payments, although they only help with the interest, not the capital, and it's normally only for 2 years. If you move out and your husband splits the equity with you then this could well impact on your ability to claim benefits, most of which take capital into account. If you stayed in your home it is likely that your husband would have to pay something towards the mortgage until the children had grown up. For most women in your position this is the best option.
Then you need to make a claim for income support, which you can get until your youngest is 5, after which it's JSA. If you find a part time job working 16 hours then you can claim working tax credit as well as child tax credit, this can work out at quite a lot of money.
You can find calculators, including how much tax credit and local housing allowance you would be entitled to at www.direct.gov.uk, so you will have some idea of what to expect.
Try the CAB again, they vary from one centre to another and some are very good. Try googling "Turn to Us" - they offer a lot of information which should help you.
Best of luck, you are very brave. I hope this helps a bit x