lol I could tell you the creative prompt for the year I sat it in. Which may or may not be the 2009 one, depending on how good my maffs is. I think it was something along the lines of
Write a story about a messy room.
There might've been a visual, if there was, then there's a good chance there was a guitar in it. Either way, it definitely revolved around a messy room.
Obviously with the above writing prompt, you don't just describe about a room - you don't even have to base your story on it (cuz that's what half the state would probably do). Btw, with creative writing at a primary - year 7 level, try to use all 5 senses if you can. I.e if you're writing about running away from something you can employ taste through bile, smell through scent of sweat etc.
Also, can't remember but you can also be given a "discuss" question? If you can, make sure you explore both sides of an argument and all stakeholders - or the primary ones if you don't have enough time. I doubt there's any structure in these arguments at the selective school level (I didn't follow any) other than common sense.