Don't worry too much about the creative writing section. Most of the time, the questions evolve around a really generalized question, however the thing is, you will need some preparation, and maybe even a few different storylines, 2-3 is a minumum.
Avoid using common stories like Red Riding Hood [this goes to 3unit english extension students as well], try to be unique. The best stories I find are actually the made-up ones about how you've visited a really old friend, your grandparents, or someone who you look up to for help or assistance.
For my story, I based it upon myself visiting an old shop that my grandparents used to own in the WW2 period..and how everything I walked past seemed to be 'frozen within a ghostly time' yet it reminded me of my real life...etc etc. My first half-yearly test scored me really bad it was an A- but after a little amendments, and 3 more copies to my teacher, she finally gave up and gave me the A+
So, just a note if you think that you're going to maybe fail in your half-yearly, put everything back in in your AP3 or AP4 i.e. the 2 exams before your HSC. One is trial and another one is a school exam.