Interestingly the party who lost the most votes to UKIP was actually Labour, they targeted a similar demographic. Most of the Conservative voters who'd polled in favour of UKIP switched back to Cons for the actual vote, tactical voting and all that.
EDIT: Labour's actually spent a lot of time in the past few GEs campaigning for the votes of middle class people in England, which are traditionally Conservative voters, presumably because the core Labour vote had no other viable options to vote for since the Conservatives don't appeal well to working class people and the Lib Dems are usually insignificant, resulting in Labour ignoring basically all of Scotland, Wales and Northern England for about two decades.
Then along comes UKIP which primarily targets the working class and, much like the BNP before it, uses pretty basic nationalist concepts to draw popular support among the working class, which swallows up a lot of the neglected Labour voters in England but ultimately fails to do anything important other than split the non-Conservative vote.
Meanwhile in Scotland the SNP has been eroding Labour support largely by being more similar to old school Labour than Labour is, resulting in a huge swing away from Labour to the SNP due to general left wing sympathies of Scotland.
The weird thing is that Wales hasn't really changed it's voting pattern much despite being consistently screwed over by basically every government of the UK from Thatcher onwards, what with the local economy getting mangled by the shutting down of industry and bugger all investment being thrown their way. Plaid Cymru has made surprisingly little gain compared to the SNP and NIs local parties.