Why can't you put it on the market? You would still probably get more than you would from one of those companies that buy properties for cash.
You may not get help with your rent, is there any equity in your property - would you be left with any money if you sold it?
You don't say how old you are, could you be entitled to any grants to get your house done up? My parents got new central heating, new windows, the house rewired and more and they just had to contribute c�1000.
Can't you buy a smaller property once you sell yours, or look into shared ownership?