House repossession - what will happen?

My parents split up three months ago because my mum was having an affair and she has moved out. Before she left, my family weren't getting along very well financially at all but now she's gone we're truly screwed for money. My little sister, who's 13, is planning on living with my mum but me and my brother want to stay with our dad because we're not exactly speaking to my mum after what's happened. My dad is struggling for money so much now, and we're receiving letters threating repossession. I'm at uni but I still come home in the holidays, but my brother's 17, still in education and living with my dad. My brother is worried that if our home is repossessed, me, my brother and my dad will end up on the streets and I can honestly admit that I have no idea what will happen. We live in the UK, can anyone tell me what will happen? Will the government help us and get us a council house? Any information would be amazing!