If you’re here, I’m guessing you’re part way through year 12 in NSW, and are probably not enjoying it too much, and maybe even trying to learn some stuff for the little quiz at the end of the year, before you move on to bigger and better things.
Notes are always a good way of learning, whether by reading their distilled information, or by actually writing them yourself. The latter method (I find) is the best way of learning material, so I wrote some notes for physics and chemistry when I was doing my HSC in 2010.
Not only did I write them, I wrote them electronically, so, by the magic of the internet, you can have them as well. For free. No cost. Without payment. Etc etc. (Also, speaking of altruism, maybe you could direct your friends here, too)
I went (fairly carefully, although not 100%) through the syllabi (physics & chemistry), just to make sure I “knew” everything, so maybe you could use these for that purpose (I strongly recommend against them being your first reference).
Some technical details: I did the Industrial Chemistry and the From Quanta To Quarks options, so they are the only ones covered; and very few of the practicals listed in the syllabus are even mentioned (that means that these cannot be your only source of information).