Hi there! I'm in my second year of the BSc at UoM, and it wasn't until this year that I realised that becoming a veterinarian was what I wanted to do. I'm planning on getting into the program as a post-grad (unfortunately I missed the second-year entry pathway since I didn't take the pre-reqs). I've spoken to other students who entered this way who has said that you need at least 85+ average over your last two years of undergrad to really be competitive, weighted 25:75 towards your last year. On their FAQ page (
http://www.vet.unimelb.edu.au/futurestudents/faq.html) they said it's usually around 81 for a CSP, but that can change, so I'm hoping for at least 85. Also, from next year and beyond, they take a personal statement which can outline animal experience, and they also use Graduate Access Melbourne.
Of course, since you've thought about the path early, you get two ways of entering the DVM. You can try to enter via the second year pathway (which takes your grades from first and second year), and if that fails, entering post-grad. What I like about the personal statement is that if you fail to get in at both stages, you can take a 'gap year', and work while getting some animal experience, so you can try entering the next year with higher chances.
85+ is definitely not an unreachable goal, in fact with a bit of hard work it is definitely realistic. Of course, make sure you do the pre-reqs (first year biology and second year biochem for the post-grad pathway, and year 12 or first year physics and the second year vet subjects for the second year pathway).
If any of this confused you, look up the selection guidelines at (
http://www.vet.unimelb.edu.au/docs/SelectionGuidelinesDVM.pdf)
I hope I helped, and good luck