Getting to Southern Ireland is not that difficult, and you have a choice of going by ferry or by plane (or if you’re brave you can go for a swim from the Welsh coast to Irish coast).
Going by ferry:
Getting to Fishguard port in Wales can be quite tricky if you don’t drive, it will take 2-3 trains/buses long wait times (days even over the weekend). You then have to wait for the ferry that will take you across to Rosslare Europort in Southern Ireland, but once you are there you can pretty much get to where you need and want to go as the bus links from the port are pretty decent.
If you drive, you have a lot more freedom and can take your car across by ferry no problem; you can see a lot more on the way there and whilst you are there too.
Going by plane:
Getting to Southern Ireland by plane can be fairly easy via central locations closest to the main airports, and the flights can be a lot cheaper than let’s say travel to ferry ports and then ferry passage costs. Though that being said, the Airliners offering cheap flights do so because they don’t always have a good customer service and you get no refunds on cancellations, no extras like free baggage allowance for stow luggage; you may be able to have a carry on without being charged extra.
If they are a low budget airline they will be a lot worse in the smaller airports as they may not have a dedicated terminal and therefore may have to wait after landing before they have an available terminal; usually they arrive 20 – 30 minutes earlier and passengers can board earlier depending on the schedule of the planes. Be aware that some airlines close the check in desks early and won’t let you check in, they won’t offer refunds either.
Going by plane you don’t get too see a lot of scenery, and it will be a lot of hustle and bustle and even delays, but it’s going to be quicker and cheaper overall.
With travel by ferry you get to see lots of scenery on the way to the ports and there will be some hustle and bustle with train transfers and buses; also running to catch trains or buses. There may be long delays and you may end up arriving at a port to find the ferry has been cancelled due to bad weather, so plan ahead and have some extra money for overnight accommodation and make the most of your extra time by the sea whilst waiting for the next ferry out.
Both options will involve a great deal of planning and there will be benefits of both ways to travel to and from your destination, so whichever method of travel you choose, plan well and use your smarts.