The Pirate Party in Manchester are doing a lot of campaigning at the moment for the by-election. They've got a credible candidate, and could actually take office, if elected.
All I can say is, if you think that the 'main' parties are either all the same, or maybe that they're a waste of space, then check out the Pirate Party. You may not agree with everything they stand for, but you can be sure they're actually going to try to do good things for you. I'm looking forward to a PP candidate in my area.