LullyDully, your class sounds rather grand. My class is in the village hall and we all wear casual clothing, what is worn varies from person to person. No question of black suits and black pumps, nor of grades of competence. We are all rank amateurs.
Our tutor varies the exercises from week to week and leads from the front, talking about each exercise before we do it and demonstrating it, then walking round helping us get it right. Nothing at all for us to remember.
How soon do you see the benefits. I am not sure. I was reasonably fit when I started so it hasn't made me fitter, but I have very poor balance, I have mild dyspraxia and it has certainly helped that. I tripped over a hoe last week and did a neat little dance as I fought to keep my balance, and I succeeded.