Plot: It's a family affair as a mother and son develop a house in Knutton in Staffordshire, a father and son work on a one-bedroom flat in London's Cricklewood and a husband-and-wife team take on an ambitious project to make a stonework shop and a brick single-storey former shop one home in Belper in Derbyshire. Martin Roberts and Dion Dublin follow the progress made on their auction buys