Interview Help

I've been looking for a summer job (going to uni in September) and just happened to fill out an online application for for Halifax (the bank). Not expecting to hear anything, seeing as I'm only 19, I was quite surprised when I had a phone interview earlier on today :-S They said I passed and answered really well and would like to invite me to a 90 minute interview on Wednesday...but I don't know what to wear?

I don't have a suit, never needed one, but do you think I should go and buy one or would that look like I was trying to act older? I feel a bit weird cause I'm gonna be going against other people, probably older than me, who want this as a full time job for bills, kids etc but I'm just scared to death cause I've never had a proper interview as such, just for typical teenage jobs like waitressing etc and I don't wanna make an idiot of myself.

Any help on what I should wear appreciated :smile: