It is always difficult to advise when money is tight.
Benefits could depend on the number of hours you work and whether you are disabled. Now I can''t assess this, and it does not harm to check with a CAB as to whether you could claim, either working tax credit with a disability element, or disability living allowance. You have little to lose by doing this.
Your husband''s income is not large and he pays you £400 per month and certain other expenses. He will not have much left for his own living costs when he has paid that. If you sell the house both of you will have quite a large capital receipt. The problem for both of you is going to be that having this sort of capital will have a definite effect on your entitlement to benefits. It would mean that you would be disqualified from most means tested benefits. Disability living allowance is not means tested and is worth exploring for that reason. In principle you would get help with rent and Council tax but your capital would disqualify you and you would be forced to run down capital, which is what it is intended to do.
it might be worth investigating something called part buy part rent, to sink your share of the proceeds into buying a share in a house and you pay rent on the share that does not belong to you. I think you can get housing benefit on this and it might be a way of dealing with the '' problem '' of having a largish capital sum, though I guess that is a problem quite a few people would like.
You may get a small sum from your husband in spousal maintenance but I can''t see it being much. I can''t see that it would do you any harm visiting a CAB to explore these possibilities.