Yes it is quite unfortunate that no one has any idea how the university system works when they are first going into it.
Basically you have a major, in your case chemistry. When you have finished your three years minimum of study, you get a degree (personally I think the additional step of giving someone a degree is completely pointless) which should be a Bachelor of Science for a chem major.
To get the chem major there will be minimum requirements expected by the university (you will have to look at the website or the enrolment handbook for the requirements). These requirements will be something along the lines of "Get XX points in level 1/2/3 chemistry, including CHEM101 and CHEM102 at level 1, and CHEM210 at level 2" or something like that.
CHEM101 and 102 are what we call papers (I made up the names, but they actually quite possibly exist). The high school equivalent is like the different topics you do within a subject (I think in 7th form biology you do genetics, evolution, human evolution, and something else).
Passing a paper will give you a certain amount of points. I don't know what the points system is like at Vic, but at Canterbury a first year paper is usually worth around 18 points, second year 20, third year 22.
So in this example, to get a degree in chemistry you will have to take CHEM101 and 102 in first year, at the bare minimum. But then you will have a whole lot of gaps to fill. You should aim to take 6-8 papers every year (3 or 4 per semester). Which means, in this example, you would have an extra 4-6 papers to take. Basically, you can fill the gaps with absolutely anything you want, as long as you meet any pre-requisites (usually for engineering classes like calc and physics they expect you to have done 7th form classes). I highly doubt psyc has any pre-requisites, which means you could take first year psychology no problem.
Because I'm doing a double major, in my first year I took the two introductory psyc courses and three philosophy courses. This meant I could take 1-3 more papers. I ended up doing the two first year maths courses compulsory for engineering majors (calculus, basically). So I did 7 papers in my first year. I've only taken 6 papers each year since. I think you have to do 5 papers minimum to be considered a full time student (so that you can get a loan if you so desire).
From psyc you can get into lots of things. A large majority of people who go on with psychology end up doing research in universities, and lecture on the side. They research such things as: personality, social psychology, neuropsychology, behavioural psychology, cognition, vision psychology, adult and adolescent psychology, family psychology and so on. Lots of options! Otherwise people get into counselling, or criminal psychology (working with prisons and police forces), industrial psychology (working for businesses, helping them get more money) and that sort of thing.
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. Law probably has the highest rate of drop-outs of any major. There is so much work involved and it's all so dull. 
I think after exams I might just hit up the Vic website and take a look around for a while.. Do people often change their degree once they have been at uni for like half a year or something? Are you allowed to if you decide you don't like whatever it is you are doing?
