In simple terms you will pay more than you thought and get less than you expected!
There is no normal so the simplest thing to do is to register with confused.com or moneysupermarket or one of the others - put in all your details and see what comes back.
That will let you see the range if costs along with potential benefits such as hire cars, AA insurance, reduced excess, etc.
Normally the websites offer you some sort of incentive to buy through them.
If you are registered with them then your renewal process becomes very easy.