You can also join a website "Dogster" for dogs "Catster"for cats , its american , but there are alot of u.k users on there. Can visit the forums on there,find out about feeding raw or home cooked.
I home cook for my dog, also rescued from the pound! He also has Harringtons dry food and the home cooked is used as a topper, much cheaper then tinned food. He also has scambled eggs or tuna or sardines in springwater once a week and of course the garlicas it does keep the fleas away!!