Redbelly
I wouldn't worry too much. FSI have a fantastic set up for training. They have advanced 'cardboard bomber' procedural trainers with touch screens to simulate all of the PL21 functions. from memory you're free to use these as often as you like once the instructors have shown you the basics. You'll learn more in an afternoon on that than you will in a week in the books.
The FMS drives the screens but there is a bit of function around the actual PFD's and MFD's too. The only way to learn it is practice, and the best place is Flight Safety on the actual sim and trainers. Relax, you'll be fine!! And as Max says you can begin pre course study through their web site.