ATIS:
No, I'm not laughing. But, recalling what the course is like, I might be feeling just a little sorry for you for the next few months.
Bottom line on the systems: in general, when you move a switch, the end result is the same, the thing either turns on or off as requested. The difference is the logic in the circuit, which will be unlike anything you've ever encountered. Sometimes the thought that they only did it this way 'cause Boeing did it the other way will pop into your mind. You may very well be right...
Perhaps the best prep would be one of those coil-bound, handbook size, brush-up books available from the larger pilot-supply store, intended for use before a recurrent simride. They give a 10,000' view of the systems and the panel layouts. You probably have one on that un-sanforized Starlifter that you're flying now.
Expect a lot of information, a couple of plateaus in learning, bouts of frustration with the MCDU, and a completely-different way of getting from A to B.
The challenge of a conversion course is supposed to be good for the brain, but this one stands out as being a little over the top.
When you begin to wonder if you can ever grasp all this, just look at someone whom you don't think is very bright who has preceded you onto the line. If they can do it, so can you.
And, if your carrier has wide-body Airbuses, you'll appreciate this course as the course for them, if you're coming off Airbus, is quite short and easy.