Apologies if someone's already linked to The Public Whip's Quick Election Quiz (I've skimmed a few of the identical 'how are you going to vote' threads but am sure I've missed at least one). Essentially, it comprises seven questions based on key issues, enabling one to gauge which party best fits one's opinions.
This site doesn't really work for me because of this: "This table shows how members of each parliamentary party voted on each issue in parliament between 2001 and 2005." Therefore it doesn't have the Greens on it, which is the party I'll be voting for. It gave me Lib Dems which is probably fair enough in the absence of the Greens.
It also bases the result on how your local MP voted on these issues in the most recent term, so I don't know that I'd worry about the result too much, Benny - it may just be that you've got a particularly confused local Tory candidate.