Cadetships are designed more for people who are very sure of what they want to do, as they do tend to lock you in and make it difficult for you to go in a different direction if you have a change of heart. If you do decide to apply for a cadetship and make it to the interview stage, expressing doubt about your career path will probably condemn you to rejection, so keep that in mind. You need to be pretty hardcore dedicated (think Prav to Actuarial Studies dedicated) or at least appear to be, as securing a cadetship is a competitive process.
I did not succeed in getting a cadetship for... erm... KPMG I think it was. I'm certainly not torn up about it though. I have a contact who's pretty high up there and closely affiliated with PWC and could have gotten me a cadetship there, but actually talked me out of it. He said that these companies care little about their cadets' study needs (despite what their propaganda says) and that they over-work and under-pay them. He recommended I take the traditional path from uni + casual work through to employment, rather than try to tackle both at once. I also like the idea of taking a post-degree gap year which a cadetship doesn't cater for, and I dislike the idea of being locked into something rather permanently, i.e. Sign contract => Work + Uni => Uni => Work while attaining CA accredition => ... you get the idea. That's about 6 years minimum right there. Sure, your resume will look better than anyone else's your age, but at what price? Aside from that, most universities only offer scholarships for full-time students... if you think you may be able to net yourself a scholarship, do a bit of research into that as well.
This is all coming from my obviously biased opinions though, so I hope someone comes along with a more positive view to help you make a decision based on more evenly-sided rationale.
Here are some websites with information about cadetships:
(with a decidedly positive skew to help balance out my post
http://www.kpmg.com.au/default.aspx?tabid=1437http://www.charteredaccountants.com.au/A116878411Anyway, have a read and have a think about it. If you decide you are interested, I can list a bunch of companies who take on cadets (not an exhaustive list, but enough to get you started).