A recent poll had the Tories 15% behind Labour, with UKIP neck and neck with the Liberals. I believe the best the Tories can get at the next election is a hung parliament if they manage to close the gap on Labour. Thats why Cameron and Farage are cosying up to each other. The only possible deal is Tory UKIP because Labour and UKIP is a non starter.
Milliband could

them big time by promising a referendum on the EU.
Anyone whose Wife has not yet settled here be warned. UKIP proposed a 5 year freeze on settlement visas in their manifesto at the last election.