Just three days in Ireland? What a shame.

As Peter says, Ryanair flies to Kerry Airport, but, unless you're willing to rise impossibly early to catch the daily 7.30am flight from London Stansted your only other option is the daily 11am flight from Luton. Catch the right train from St. Pancras and Luton's only 25 minutes away.

If you want to catch some great scenery and music sessions, I'd strongly recommend flying to Belfast, hiring a car and taking the coast road all the way round to Derry (from whose airport you can fly back to London).

I'm presuming you're going to be based in London or thereabouts. If not, you'll waste most of those three days travelling back and forth between the UK and Ireland.