I didn't do science, neither did my girlfriend, or most of the other people in my degree. It is totally not necessary.
Also, with relation to the above post, you dont have to be great at English and Maths. Of course it helps, because you'll spend your life writing research reports and essays, and you'll have to do stats. However, my girl didn't do maths for the HSC (in fact, she dropped it in year 10), so dont give up hope if it isn't your strong point. Additionally, the maths you learn in high school is almost irrelevant, because its stats, not maths. They dont even teach stats in the HSC course, so, when you do get to uni and do stats, it will be a totally different experience to your HSC maths.
Hope this helps
