Insurance quote might be interesting for a learner driver Q7.... nice car though. In my last job I could "borrow" cars for the weekend, the 3.0 TDI engine in various audis is a cracking engine, copes with the Q7 weight no problem. But the 4.2 is a lot more fun...
+1 on the 4.2
I had a brand new 4.2 A8 for just under a year back in 2006 and it was epic fun to drive. I almost cried when it went and I was back in my mr2 turbo

Just asked my dad about insurance as a named driver, he says it's better nowadays because some policies allow all drivers to accumulate no claims as well as the policyholder. This is obviously what you want for the long term so you can build your own no claims up and not have to stay as a named driver.
25 was the age which really saw prices go down before as I remember paying £1500 to insure a £5k Vauxhall Calibra at 23 third party fire and theft. Less than 3 years later at 25 I only paid £1100 fully comp on a £65k Audi.
Prob worth going onto confused.com or gocompare and just give it a spin to see what kind of numbers come back I'd say would be the best bet. Once it comes around to doing it just try to drive the companies down by ringing around and saying well x can do it for this can you match.
I'd say whatever way you go for a first car Q7 is going to be lumpy
