I'm pretty certain that you can join if you want to, you should call them up or text them to confirm.
They teach you all of discovery, module A, module B and module C.
In discovery, they firstly deconstruct the rubric for you. Then they teach you how to approach unseen text questions. They also make you answer several exam-style unseen text questions at the end of the lesson. Following this, you would hand in your answers, and you will receive your marks & feedback the week after. The feedback is quite harsh, which allows for you to improve a lot. After learning unseen text, you will be taught how to structure your discovery essay and creative writing. They give quite a lot of resources (which includes exemplar responses from past students), which will guide you in creating your essays and creative writing.
In module A, module B and module C, they will deconstruct the rubric for you (again). They also provide powerpoints and handouts (involves exemplar responses from past students) which demonstrate how you should be writing/structuring your essays in each module. Similar to discovery, you will have to write up some responses in relation to what you have learnt that lesson, and you will receive feedback in the following week.
I'm pretty sure that they will be just as good as teaching Advanced. You should be fine