It depends on whether there is any other household income. We didn't qualify as I was still working but I believe that you can claim mortgage relief (the mortgage equivalent of Housing Benefit) after 13 weeks if you qualify. The job centre will be able to let you know more if required
They will only pay the interest by the way so you will have to ask the lender to put on you on interest only. They also pay at a standard rate of interest of 3.63% so if your rate is higher than that you will have to cover the difference.