It's worth pointing out these elections aren't a typical cross-section of the population too - this is predominantly the countryside voting, not the cities, so results are already skewed in the direction of the tories & the reactionary right.
Looking at overall percentages is meaningless from this sample, since for example UKIP's score is a percentage of *something*, but that *something* isn't the same as the full UK electorate. It's going to exaggerate their capabilities. Sympathetic media will focus on their percentage as though that's what they're capable of across the board. I suspect there will be some intelligent weighted analysis somewhere, but the Mail et al will be calling it for UKIP and calling on Dave to steer further to the right.
It was a similar thing with the BNP, media pointing out a few elections ago that they'd won 8% or whatever, but this was where they'd stood - places where they had some support, and nothing like they'd get if they fielded candidates everywhere.