hi everyone, newbie in the house

i got myself a black mk4 gti a while back,always loved the golf, legendary little motors, anyway i wanna polish her up a bit so any advice would be really appreciated,
cutting to the chase, i got what i think are 15'' arvun (sp?) wheels which are a bit lame and i wanna beef them up a bit without going 2 too much hassle right now, can i put 18's on without modifications?, if not how bout 17's?
also, i wanna have a dent that some drunken reprobate put im my door last week taken out, got a few places 2 phone, but was wondering if anyones tried and tested anyone in particular in the luton, n.london area?
thanks
