Oh, sounds just like a workshop, not like you have to impress anyone
The thing about those, depending on whos attending them, you could be really out of place.
If its one in a small conference room in JHE or MDCL, chances are you'll have a bunch of upper year people (or PhDs) and they may be in suits.. if its a lecture style event, then you can get away in casual clothes! (i.e. lecture hall room)
I'd still just wear a pseudo-fancy shirt and probably decent shorts; nevah jeans!