Actually, Kempez is right.
Being in the age bracket of 17-25 places you in a high risk zone. This isn't your fault though, it's purely down to your brains development.
Not to go all deep here, but the frontal lobe (The part that controls your ability to detect risk, hazards etc) is not fully developed and that combined with inexperience and overconfidence of being a new driver is a recipe for trouble.
You are 7 times more likely to crash within the first 250 miles.
Carrying passengers also carries a risk, so ease yourself into that...
Single Passenger – 39% more likely to crash.
Two Passengers – 83% more likely to crash.
Three or more passengers – 182% more likely to crash
So be careful!
As for pass plus, I found it very beneficial. I too passed with only 3 minors....but pass plus taught me how to drive *Safely* on motorways, plan journeys and made me feel safer...
It should cost in the region of £150 and (at least, when I was getting insurance) saved me about £400....
If you haven't already got insurance, I'd suggest taking a look at admiral online quote....add your gran as a named driver on your own policy (So you build up your own no claims...)..
I added both my folks to mine, dropped my original quote on a 1.1 106 from 2200 to 1200 first year....that was without pass plus. I think it eventually dropped to 800 or so...
Hope that helps!