Thanks!
So I'm gathering that you study a particular topic throughout an AOS, and you must go out of your own way to develop your knowledge within this particular area and apply that accordingly into a SAC? *That's what I gathered from the term case study, unless you mean a case study that comes with the SAC and you have to quickly dissect it?* I think the first option would be awesome, because that'd add so much more of a challenge!
House of Cards is amazing.
Not exactly. The teacher will go over the theory for the relevent AOS, and then you'll look at case studies together as a class (teacher might talk about a particular example, or you might watch a video, or get something from the textbook, or another student might offer to make a presentation on something that they know a bit about etc., etc.), so that when you go into the SAC or exam, it's likely that the entire cohort will use similar examples to address questions. You certainly won't be given a case study for the first time for a SAC! More likely you'll be given a broad question that you can tackle a number of different ways, and you just saturate the essay/short answer questions with examples.
That being said, at my school (so I don't know if this applies across the board), there's usually one political cartoon in each SAC, which does refer to a specific case study (usually worth 1/2 marks to explain the meaning of the image). You'll have looked at it as a class, so it shouldn't be too throwing.
Of course, you're well within your own rights to find examples of your own (it's encouraged, in fact). So long as you know them in sufficient detail, it can only help to do independent research.
Good luck!