Thanks for the intro Nick. Yep, I'm in the north (but from England originally). Not many clubs up here, but there are loads in Dublin. I think on the whole that the clubs in Ireland mix together frequently and you get a bit of a 'one happy family' feel in most clubs. Although I train in the (far) north I often go down Galway (for a summer school), and have also been to courses in Dublin and Sligo.
I think the club you'd prefer would very much depend on what you are used to at the moment.
Here is the aikido in Ireland web-site which lists almost all the clubs in Ireland:
Good luck with your training, and if you are ever up in the Coleraine area you're welcome to drop in!