The Irish County tartans came into existance pretty late in the game, relatively speaking. I'm thinking mid 1800's. M.A.C. Newsome and others can set you right on that. Since that's the case, there's little connection between old Irish clans/families and the county tartans.

That said, a lot of them are lovely. County Cork happens to be my favorite, but I like several of them and I think a kilt skirt in one of your favorites would be a very nice thing.