Are you talking about classes?
I would be absolutely stunned if it cost full price - after a year of being on the weigh team I have never ever seen it as being full price (£14.95) - its always been £9.95 or £10 depending if its the half price joining fee offer, or first week free offer.
Of course this is no guarantee - if you want to be sure, give the consultant of the group you want to join a call, they have a chart which shows which offers are on when (we keep it on the desk at group so as it also has all the prices for the various countdowns, OAP rates etc)
