I have driven in Ireland many times and even though I drive a manual transmission here I always opt for the auto. When you first start driving there's a lot going on that is really different and being on the "wrong" side of the road and vehicle can affect your spacial awareness. Just look at the other cars in the rental lot and notice how many have severely scratched and damaged rims.
You do get used to it eventually and will soon find yourself quite confident.
Speeds on Irish roads especially the Regional roads will shock you at first. A twisty road with poor visibility on curves and barely wide enough for two cars to pass will have a seemingly suicidal speed limit of 80 kms.Meeting a tour bus or large truck on one is always an adventure.
That being said renting a car is the best option for Ireland as you will be able to get to places not visited by tours and at your own pace although rental prices this year have spiked.
I have also had some adventures with the gps as well as it has tried to take me on some roads that don't exist and sometimes won't recognize some Irish destinations.I had to consult a map and try nearby locations then navigate to some spots.