I’m not sure where to put ideas but a Kudos: Politics ala Kudos: Rock Legend except with a political party would be a fantastic idea, imagine it, you riding your way to the top of either Labour, Lib Dems or Tory ladder or starting your own party!
I don’t know of any political simulators for the UK, but if you’re looking at something like this from an American perspective, there’s Political Machine 2008. It’s put out by Stardock, and it’s also DRM free.