Trying a class, any hints/warnings?

I've found out there's a place in Portsmouth that does Scottish broadsword and some quarterstaff work and am off to give it a lookie tomorrow. I wanted to ask though if there's any advice on trying weapons arts in general, or any warning signs to look out for?

Never tried weapon work, and I'm aware the club and HEMA type things are meant to be about the history first so my usual ways of judging schools from a sport art basis is a bit useless here.

Also, is this finally something I can rock up to in jeans and a t shirt?