H.mcdaid
Congratulations on your offer, I've just completed my APL portfolio and have been given an official offer. The APL portfolio is for the university to check that you are able to actually complete the course in the 2 years rather then the 3 years you would need for undergraduate.
It can seem daunting, but all you need to do is prove your degree certificate, degree transcript, CV, complete the life science work book, which covers the basics of human biology, and if your first degree was more then 5 years ago you will need to send a supporting personal statement to show how your degree has been helpful since you've left. Anything extra, the advisor they give you will help you through it.
Try not to panick, there success rate for passing APL is really good. Plus they have workshops to help you through it