@ Maniac, if you want to tactical vote against the BNP, probably your best bet is either UKIP or the Greens, maybe Lib Dem. Sadly I doubt there will be much you can do to stop them.
@Ghost, I presume this means you'll be voting Tory?
@Hereward, I presume this means you'll be voting UKIP? To that I have to add one of the Pub Landlord's catchphrases, "Shame on you!"
@sceptic, I have a friend who would naturally vote CDU, but for the C part - he's not a Christian, and therefore he does not want a Christian party representing him! Due to the way German politics is, I think he normally ends up voting SPD, which I personally find a little odd. But then German politics is a strange beast, given how ridiculously easy it is to have a hung parliament as there is currently. In fact, it almost seems set up to deliberately create a hung parliament.
Personally, I will be voting for the Conservatives. I am pretty much a Tory through and through (should that be hyphenated?), although I am definitely a lot less right wing than your typical Tory voter. They just happen to be the Party that most corresponds to my views. Plus I live in South East England, so you can't really expect anything else!