I am 28 and it costs me £387 fully comp with all bells and whistles. OK 6 yrs no claims helps.
Direct Line (Ceapest by far) just limit your millage helps.
1st Year if owning a B is the most expensive, group 16 LHD. after that it goes down quickly as long as you have made no claims.
My 1st year was £698, 2nd yr £480, 3rd £387.