You need to have attended a set amount of classes (7-14) and be assessed for safety before attending these classes. This activity is phone to book, so you will get the chance to speak to Sammy who will discuss if you are able to attend this class.
The supervised training is an opportunity to practice what you have already learned in class. You have to have some aerial experience to attend these sessions, they are not for complete beginners. It is not a space for learning completely new things or asking the supervisor to assist or teach you.