Martin,
First of all, congratulations on passing your driving test. It is quite an achievement when you get to have your full uk driving licence. The deal you've got from Diamond is pretty good to be honest, hence I'm curious to know your age because normally you don't really get cheap car insurance for new drivers. I suppose you've been added as a named driver on your parents' policy by the looks of it. Just remember that as a named driver, you shouldn't be using the car more often than the main driver because Diamond can say you were fronting if you ever make a claim. Well good luck with the driving and be safe.