hey dude,
i saw your message on engineering on the bored of studies website. Im currently in my first year of uni at sydney uni doing 'Flexible first year engineering' - in this course you get a general overview of each of the engineering disciplines (Aeronautics, Mechanical, Mechatronic, Civil, Chemical, Biomedical). If your unsure as to which engineering discipline to enrol in, i would highly recommend doing 'flexible first year' engineering at Sydney Uni. I was like you when i enrolled in egineering - i was tossing up between Aero and Civil engineering. Like i said, you get a general overview of each engineering stream. You have to pick which stream you want to focus on and enrol in it at the end of your first year at uni (you still complete your BE in 4 years).
I found that Aeronautics is heavily based on mechanical engineering in the first 2 years. After that, you concentrate mainly on the 'streamlining' of objects. Bear in mind that aeronatics is not just dealing with aircraft, it also deals with low velocity objects such as cars and vessels (ships). It is probably the most specialised stream of engineering and also has the highest drop out rate. i was told that 70% of students get jobs upon graduation. Given that only 40 or so people graduate with a BE (AERO) each year, your job prospects would be fairly limited. You'd probably have to go to the US or Europe for a long term career in the industry. (I know a guy who got a cadetship with BAE Systems - he is now designing the front spoilers for BMW Williams F1 racing team!!). If your looking in a career with aircraft, youd probably better off doing mechancical engineering (for example, QANTAS only has a handful of aeronautical engineers - they have heaps of mechanical engineers. This is because QANTAS doesnt design planes, they only maintain them).If you can get a decent job in the industry, your set, but its hard to secure a decent job (especially in Australia).
In regard to civil (structural) engineering, your dealing with designing the internal structures which support buildings, bridges, other infrastructure, etc. All civil students do a core program in the first 2 years. it is only in the final 2 years of your course that you do about 4 or 5 structural subjects. There are other civil specialisations (structural, geotechnical, environmental, project management) or you can elect to do a plain civil engineering degree (no speciailisation).
Ive decided to do civil (Project management) (Im doing BE/BCom, so i thought this degree would go well with a commerce degree). Hope this info helps. good luck with your HSC mate. - Andrew.