That's very interesting, and I see you have set yourself some clear goals, which is great.
The problem is, I'm not 100% sure what I like. For years I had really wanted to do scientific research, probably in infectious diseases, but then this year I met so many problems with getting into USYD and UNSW (they won't accept me because I'm 'too young' - mind you, I'm 20) that I started looking into other fields and liked engineering (but to a lesser extent than infectious disease research).
Now all of a sudden I have an offer to study PhB; I didn't do year 12 and nor did I submit an application, so I'm genuinely surprised at the offer (and insanely happy). So now it's like: go with engineering and have a stable income, housing etc. or do PhB and rely on scholarships for the first year, then I don't know... it's all very difficult and confusing, especially because I have a lot of pressure on me that no year 12 leavers would have.
Can I ask what residence you'll be at? I'm looking at Fenner Hall (for numerous reasons).