Vote Ukip.

Only in the event of needing to prevent a leftist from taking a seat would I consider voting for anything other than the-party-which-threw-it-all-away after May 2014.
On a scale of one to ten, I'd probably give Ukip 3.5; The Tories 2; Lib Dems 0.5; Labour a big fat zero and The Greens -4.