What to wear to an "extras" interview

Hey guys, I'm new here so i'm not sure if this is the right place to post or not. Anywho, i've got an interview next week and an "extras" casting agency and was wandering if you guys had any tips on what to wear? Is it like business attire or should i wear something a bit more 'funky' or "smart cas." etc? Any tips/advice would be much appreciated!! :) Emma