Hi Migg48,
Most of the FSI manuals are through their app now, you should get sent all the info prior to the course. If it hasn't arrived, just give them a call or email and they may send them to you early with login details for the app etc. If not, or if it's still too far away, try code7700.com. It's a guy who flies a G450 (fairly similar to 550). He's put together a pretty impressive website with all the systems as well as some other great stuff. To be honest, you'd probably pass a written test based on reading his website alone!
Hope that helps.
Enjoy the Gulfstream.