Hey, I'm in medical science too. But second year. I did all the subjects you did and I bought all my textbook from co-op book shop. Big mistake! The books there cost around $155 (you get about a $10 discount if you're a member). You can get books from many different places for much cheaper! The maths books you can buy for about $20 from a store near broadway (your lecturers will tell you the address). The chemistry, human biology and psychology books are much more expensive (around $155 each)
To find out what textbook you need for each of those subjects, go here:
http://www.coop.com.au/bookshop/action/DataSubjSelect and type in your subject code.
Go on bookdepository.co.uk to buy your textbooks. They are about half the price of co-op books, however, delivery takes about a week as it as UK based store.
If they don't have the book, buy one on ebay, you can buy brand new books for very cheap too. (that' if you trust ebay, I do and I bought 2 brand new textbooks from there for about $65 each)
You could also consider buying second hand. I bought my psychology textbook second hand, we got told to buy the 9th edition, but I bought the 8th for half the price. Your lecturers will go on and on about how important it is to get the new edition, but believe me, it's not. The content is almost identical, but the page numbers are different. I got a distinction in PSYC1001 by just reading the relevant chapters in the old edition. So you are in no way disadvantaged by getting the old edition. You will see heaps of fliers around carslaw building that students post up trying to sell last year's science textbooks. Getting an older version of human bio or chem textbook was actually encouraged by my lecturers last year. They said the content is basically identical.
And yes, you do start learning in your first week, however the first lecture of each subject is basically an introduction where they tell you everything you need to know; textbooks, assignments, coordinators, etc. But from your second class, you'll actually start learning. If you have any questions about uni or med science, feel free to ask me