Hi. May I be the first to Welcome you to Ireland.
Well there's good news and bad news for you. The good news is Ireland has (believe it or not) some of the best waves in Europe, if not the World. The bad news is, as you said, cold water.
A couple of things for you to know:
1. There are no waves (except once or twice a year) near Dublin, so if this is where you're headed you'll have to drive for about 3-4 hours to get to the west coast to get out.
2. Yes it's cold but it's not that cold. You'll need a wetsuit (I'd recommend a 5/3 all year round really) but we're not talking artic conditions here. I did surf when there was snow on the ground once and the water was actually fine (once you had a wetsuit hoodie on as well).
3. It's becoming very very popular. When I started about 3 years ago you'd see maybe 5 people or none in the lineups (especially remote parts)....now you'd see 20.
4. Surf spots:
South: Cork and Waterford have some good breaks but can get ruined by wind (predominently SW winds in Ireland)
West: Kerry, Clare (Lahinch is practically like Byron Bay it's so full of surfers...see links below) have some great spots but again suffer from the wind sometimes.
NorthWest: My favourite...Mayo, Sligo and Donegal: Excellent surf spots, the SW winds are offshore here and you get the likes of Easky (10 ft tubes)!! This is a world class spot...
North Ireland: Lots of great places up the north too but slightly more crowded...
follos the links for all the surf clubs etc which will give you more info.
Finally - if you come here you will have some great surfing and some great craic (fun). The surf is getting more crowded but if you respect the locals (especially at the world class spots) you'll have no problems....we're a very friendly nation. There are still loads of places to explore that have great potential too.
You might take a little more time in your popups though with the wetsuit on!!!
Best of luck and see you out there.