Well since I know nothing about the actual class, I can't speak to whether there will be a little "test" for you to remember. I can suggest clothing though. Since it's English I would wear breeches if you have them and tall boots. If you don't have tall boots I would think nicely cleaned paddock boots and half chaps would be just fine for a schooling show. For a shirt, just a nice polo tucked in could be good or if you want to go a little dressier, maybe an English show shirt with a show coat. You might want to check with whoever is hosting the show for any special dress code. And of course, wear a helmet and black gloves.