errr let's see..
2 weeks: So you should be in the finishing stages of making your notes (if that's your THING) OR you should be fully content with the content you've studied (SEE WHAT I DID THERE lel)
Maths 2U: 2 weeks, textbook is really not an issue here. Identify what topics are going to be tested in your half-yearlies AND then check if you completely understand them. If not, now is the time to do revision exercises in your textbook. If you have the Fitzpatrick 2u textbook, that's a great textbook as it goes from easy to hard and lists the stuff you really need to know. But yeah once you've familiarized yourself with the questions, you can move onto the next stage, which is past papers. Now there are so many past papers floating around the web, but if you wish to have hard-copies, purchase/borrow a Success One Maths from your library/post office, and do all the questions from the past papers in it. Once you do all the past papers, you'll be ready and you should be able to answer any question even if they try to trick you in a question.
English Advanced: Now english is a bit tricky, because you can't exactly cram this subject. I reccommend you creating notes on your module text and then compiling them with quotes and techniques/ as well as character analysis and all that shizz. Once you've done all this, do past paper english questions and write some essays. Essays are really the hardest part, because writing an essay under 40 minutes is REALLY hard. So do some practice, since practice makes perfect. Do several past paper questions from previous HSC's and you'll find yourself really accustomed to it. Make sure you really remember the stuff you made notes on so you can add that into your essay. Once you've finished doing an essay, submit it to your teacher for marking and he/she will provide constructive feedback which you can use to integrate for your essay.
Chemistry: Seeing as i don't do this subject, i'll just say the generics. Check the topics tested, and revise with the syllabus. Use an Excel book or a Dotpoint Chemistry book so you can revise to the specific dotpoints. Also do past papers, it's really crucial you do this, because then you can put your knowledge into practice. Now that you have two weeks, allocate time to do both things, dotpoint revision summaries and past papers.
SDD/IT Multimedia: I have friends who do SDD, and whilst i don't do the subject; i think this subject requires you to understand all the content required. So invest in a Excel book (I found it helpful for IPT, should be helpful for those two subjects). Also do some past papers, so you can check if you know everything. Remember practice is the key.
Don't stress because it'll be over before you know it. Make sure you allocate your time appropriately, and try not to overthink shit. Try to avoid cramming cause it'll generally end up in over-stressing (i always cram and that's normal but try to keep it to a minimum, it's never good but it might be your style of studying, but yeah it's your choice. GOOD LUCK DUDE!