TortoiseSVN cannot be installed at school. To get around this (such that I could develop here (by here, I mean at school)), I went looking for another client, and came up with SmartSVN.
It's written in Java, so it works on any platform, and it works pretty well. It's slightly harder to set up, but once it's there, it's great.
It can be found at http://www.syntevo.com/ or downloaded here.
I'll be back at school tomorrow to work more.