Its been a while since MrsOpus and I were there, but there are now very low fare options from London to Ireland. Ryanair.

I would definitely drive while in Ireland. There are very few, if any, viable alternatives. I guess, the bus. Just follow signs to the next town on your map. Roads are narrow, hedgerows often on the sides, but once you get used to the right hand drive and learn to look left, things will be fine. Being ambidexterous helps as the gear shift requires use of ones left hand and most cars are manual.

The wild Northwest coast is beautiful and friendly, albeit a long way away. The Southwest is probably more attainable and is equally interesting.

Enjoy.