Spend as much as you can on the amp and maybe a bit less on the geetar… My favourite guitar’s an old Squier that cost me £90 (OK, needed all the electronics hoovered out and binned but all in, under £200) and my next is an old Fender HRR strat that was £250. Went to Denmark Street one day with a grand and a half to buy something new, found nothing that I liked more so bought some pickups for the Fender and a prettier strap 😉
You can play rock and metal on pretty much anything, but, if you want to really use the trem then you should probably consider something with a floyd rose, which does narrow the options. Ibanez are the obvious choice really, remember some cheaper locking tremelos are a bit crap.
Otherwise, something solid and humbucker- equipped… I’ve a real soft spot for these:
http://www.gak.co.uk/en/squier-tele-custom-black-maple/6508
Well equipped, mostly play well and a wee bit more distinctive than the usual black SG/flying V/Ibanez/Les Paul.
The PRS SEs that Rusty mentioned can be good too, the quality of the fretwork used to be incredibly random though, but maybe that’s improved. Otherwise very good. Epiphone do some decent models though they get sneered at a bit, but you tend to pay over the odds. I’m pretty out of touch though, fell out of playing a bit… Used to be Vintage were the kings of the £300-mark, not sure that’s still true.
Do consider something used, guitars tend to get better with age after all. My SG that I used to have cost me something like £300, would have been £900 new at the time, it wasn’t worth £900 mind 😉 But having a proper Gibson SG felt a bit special.
I don’t know the newer Vox stuff but like Rusty I’ve got an older one, a blue AD60VTX and it’s a great bit of kit. See if you can budget for the floorboard, I sold off almost all my FX after I got the Vox. Pedals are a lot of fun.