when i try installing it through origin it just keeps coming back to the same page that has a button 'ready to install' I press it and then nothing happens - after a while it comes back to the same screen
Have you tried uninstalling and then reinstalling Origin? I know that has fixed similar if not the same issues. I'm not sure of any legal way to install it from either the disk or as a download from Origin. Even the disk way requires large patches.
does it appear to be downloading? have you utried asking on the origin forums, you know where the people you brought the game from work and get paid to fix the problems with their games, this should always be your first port of call. The chances are that they have seen this 100's of times and will have a solution, we wil have seen at most 10's of issues and individually only seen one or two installs ourselves.