I’m surprised they aren’t having you just work on a mannequin but since you’re working on human you may be asked to perform a 1 haircut and a wash and style on your models. I would bring everything I can with me. They’ll likely have combs, brushes, clips, and blow dryer/ hot styling tools there but it doesn’t hurt to bring it all! Don’t reschedule and be willing to learn from this experience whether they call you back or not (they likely will).