I'm not a fan of group tours but some folks love them and it does take the stress off for planning but gets rid of a lot of opportunity to see things off the mainstream. Ireland is so easy to get around in that I'd certainly do it on your own.
We went for 10 days last spring and had a wonderful time. Flew into Dublin and spent 2 1/2 days there (Churches, Guiness, Post Office, Historical Prison etc). Caught the train to Cork and saw the sites like the english market (city double decker bus out to Castle Blarney. Wifi enabled, clean and safe busses). Rented a car at the airport and went to stay at country house in Mallow where we relaxed and I did some trout fishing. Drove the coast up to Galway via the Cliffs of Moher and such and turned the car in. A couple days around Galway (loved it) and then train back to Dublin and a day in Dublin and home.
People are amazingly friendly. Scenery, especially the west coast, is stunning. English is the most common language followed by Polish.
Navigation with good map and GPS was easy and although it had been a decade since I'd driven on the left it was no big deal and I returned the car in the same condition I rented it (still, get all the insurance!
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