i did my class one last week, jeans and trainers were fine, and having paid £400 for the service, i wouldnt expect to be told of a dress code so just go as you feel comfortable, no-one is judging you by how you look, just how you cope with high frequency strobes
A question slightly off topic; does it always take roughly 2 weeks for the medical to come through? only ive got a place on a sponsored training scheme, dependant on this class 1, which im scheduled to be on in april and with lots of other sorting out to do in a very short time.