[JSDude1]

A UKIP win the European elections would do 3 things:

1) Give UKIP momentum (and voter practice at voting UKIP) going into UK elections.

2) There are local elections in which UKIP hopefully picks up more seats so that their good governance is put into practice and builds a base for UK Parliament.

3) Topping the European elections would give them more people in the EU Parliament with a bigger voice to oppose what the EU is doing.

[Winniesboy]

While there may be the consequences you mention, they're not all that likely. Mid-term local election results here are as poor a guide to performances in a subsequent general election as are European Parliament elections, but for different reasons. The fact that this time they're on the same day will at least boost voter turnout for the Euro elections, as turnout is usually higher for the local ones. If Ukip win a large number of local wards, as is likely, for that to be of long-term benefit to them the quality of candidates will need to be a lot higher than it has been. All too often hitherto councillors elected on a Ukip ticket have turned out to be unimpressive, to put it politely.