Me and the misses do our cars with Tesco. Fortunately neither of us have ever needed to call them out so i'm not sure what the service is like but it's there for peace of mind if ever we breakdown.

http://www.tescobank.com/personal/fi...own/index.html

There's also Asda and they will also offer multi car discount i think.

http://www.asdafinance.com/insurance/breakdown/cover/