Hey, if you're reading this!

I'm a 13 year old guitarist that is looking for some advice.

Basically, I'm worried that my tone will sound bad, as my guitar is made for blues and came with custom pickups that (i think) were made for blues/jazz styled playing.

The tone i want is a Classic rock sound (Metallica, Nirvana type sound) and a good clean tone aswell, and i have a budget of around 400-500 pounds.

I'm worried that my G&L Tribute Ascari GTS (the guitar with the bluesy pickups) won't sound decent when plugged into an amp with a lot of gain. Should I be worried? If so, what pickups are decent and cheap? And what amp has versatile enough to have a good clean but a ballsy gain?

Sorry if you found this confusing... I'm pretty crap at English :P

You definitely shouldn't be worried. That guitar looks like it is more than capable of grunge and metal, it has coil splittable humbuckers so you can get a range of sounds.
It's not gonna sound as good as a mustang or a guitar with really high end humbuckers, but the difference is small (particularly to your untrained ears) and the price difference is big for a 13 year old.
A more important think to be thinking about improving would be your amp, anyway.
Besides, you have more important things to be worried about, like, does that girl sitting across from you like like you?

If you still want to talk about tone, head to the GG&A subforum.
But boys will be boys and girls have those eyes
that'll cut you to ribbons, sometimes
and all you can do is just wait by the moon
and bleed if it's what she says you ought to do