There used to be a benefit that covered the interest on mortgages taken on before unemployment. I don't know if this still exists, although with interest rates at their current level it would not be an expensive thing to do given that anyone who qualifies can get a rent allowance, so I do not see why too many will be homeless unless the price of their letting is ridiculously high as councils do not want thousands of rehoming cases on their hands, so might be sympathetic.
As far as property values are concerned, prices certainly will be driven down by landlords selling off their empires cheap. Last year I sold my house at a reasonable price. Events meant the sale fell though, but I won't go into that. Just around the corner is an exact copy of our house being let out and the owner is selling to get it off his hands. He has priced it at £32k less than I sold ours for last year. That is a huge drop, but it will affect the value of our property for years to come.
Mike.X