Fusions 'Choice Membership' help!

[Junad1997]

Hi, I am 15 years old and I am a student, as i I cannot work at my age and have no job i don't have enough money I am limited to my options, I would like to join the gym at the dulwich leisure centre. I have enquired about the junior gym uses and costs and am waiting for a reply via email, however I also noticed the Centres 'Choice Membership' it mentions that most of the things are free when you apply for the card, however after looking deeply into the terms and conditions and what I have applied for I still don't understand, is there a catch? Do I have to pay anything after using the card - example, would I get a letter every month telling me what I have to pay for after using there gym 17 times? Or do I just get the card and use it freely? Someone please help me. Thanks in advanced