thanks to all
Thanks for the help. I'll be in touch with a few of you shortly via PM.
I did find the Ulster Flying Club online and sent an email to an instructor there.
We're really unsure of where we'll end up on our vacation. We've got friends in Dublin and have not been to Northern Ireland before, so that's why we've chosen that direction. (Yes I'm aware that Dublin's not in NI; we'll just fly in and out of Dublin.)
Please keep the suggestions coming for Flying Clubs and particular sights to see (from air or ground). We'll be traveling in late July, so we're still planning.