Brb collapsing, no uni till September 5.
Why until september 5? :O
I'm going on exchange to Penn next semester 
How'd you manage to organise that? I'm interested in doing something similar (although I've heard it can be really hard to organise exchanges for biomed students ._.)
Basically your only window will be Semester 2 of next year, you can do it though. I know someone who is going on exchange at the same time as me who is from Biomed, and she took Human Physiology and Principles of Human Structure this semester (the science subjects) so that she doesn't have to take Human Structure and Function next semester and can just take Science electives etc. overseas...
It's not a big deal in terms of content or disadvantageous to you, the subjects are very similar - only a few differences between what is covered between the two. For instance, in the exam I just took for Principles of Human Structure they included two questions from a past Biomed Human Structure and Function paper. So the level of overlap is very high!
I'm not sure if you guys have other prereqs aside from those, I'd assume not? You just take all the core, or supplement for core in the above case, Semester 1 2013 and then in Semester 2 you are free to use up your breadth(s) and electives (which is best because it's more flexible).
You just have to choose your institution wisely!
In terms of organising it, for that time frame you'd be looking at handing in your application to Melbourne Global Mobility in November of this year (so you should have decided where you want to go, gotten subjects approved by the relevant faculty, gotten permission to take Science subjects instead of your Biomed core and worked out how much everything will cost you). Then you wait to receive your exchange offer from your institution. The way Melbourne typically works is that if they nominate you for an exchange program, that institution is required to accept you to meet their quota for the amount of Melbourne students they need to take...so once you get past the nomination hurdle at UoM there isn't much competition for institutions. For Penn, this year you needed an 80% average to get nominated and last year you needed an 86% average for nomination. It varies from year to year, but for Penn and Berkeley (if you're planning on going to the US) you'd be wanting 85+ to be on the safe side in terms of nomination, it can get pretty competitive - mostly for Berkeley, but recently there has been a huge increase in interest in Penn. Nomination cut-offs are just based on demand, the minimum average you need to go on exchange is 65%.
For my subjects, I'm taking all the med prereqs now and when I get back as the chances of finding a subject you can credit as 'exempt' are low. I am taking one exempt subject at Penn though, but it's just a third year elective. My other subjects are looking to be a genetics elective, a physiology elective and a criminology breadth. It's best to choose subjects that are electives because the institution will always put their students in classes first, and if there is no room for you they will ask you to find another subject - not so great if you're trying to do core subjects or parts of your major. You just need to be flexible and that's why it's best to take what's required at home.
Hope that massive barrel-load of information was enough, and probably ten times more than what you were looking for haha.