Look GiantSloth, dude, I don't think there is any point in you knowing, but lets talk about this:
If you hold the fort on all your subjects and perform about the same in the exams you will get, this is hard to predict, but according to SAM (Student Assessment Modeller) between 50 and 60 (SAM said 57ish) and that is assuming you do English ADVANCED, if you do STANDARD then it will be a few points lower, surprisingly not many though.
If you perform roughly 5 marks better in every exam (which for several reasons, to get a mark 5 marks higher in every subject you will need to, in reality, get a mark about 10 marks better given your average rank) And there is no reason why you CANT! It's called study, then you could get up to about mid 60's (SAM said 68) However if you go worse by five marks in every sub then you will get mid fourties. And yes PRINCESS ranks come into working out your UAI...well, your HSC marks rather. Which are then used in your UAI.
If you do what, 3 days study before this English Exam, then three days before your next one, and just do full study for each exam. Try to go really well in PE ... and you should go better if in every subject. Fuck it dude its just a poor UAI, who cares in 2 years. Princess you aint gonna get 70.