I live near Brighton and go there a fair bit, and I really don't think you'll have trouble finding fellow metal heads to hang out with! There may not be that many at the university itself (I might be wrong of course) but there'll be lots of events and things for rockers like you. Just try wandering around the Laines, I'm sure something will catch your eye.
No worries mate. Brighton's a notoriously laid-back place and whatever you're into you'll probably find here. The music scene is quite vibrant, good clubs, generally a good atmosphere all round. I'm sure you'd love it.
I have a conditional for Biochem at Sussex this year, but if I don't get it this year, I'll be applying again next year! (Who wants to compromise on which uni they go to?). I am also a metalhead geared towards thrash metal such as Megadeth, Testament, Metallica, Overkill and such. My roots are grounded in classic rock and metal however (likes of Gn'R, Ozzy Osbourne etc).
Need some metalheaded contacts for the sake of sanity...
What housing have you firmers applied for? I put Brighthelm top, then Lewes Court ph1, Park houses, park villege, Lewes Court ph2, Swanborough, Northfield, Stamner court, off campus with East slope coming last.