Thanks to Lisjb and wexflyer, I have managed to get a much clearer idea re the application process for citizenship. The 3 generations includes myself: the applicant, my father and my Irish grandmother - it's just as well that I turned to rootschat for help.
I can use the Ferns parish link to get baptismal records for my distant family this will help my ongoing Irish research. It's all much clearer, thanks, Geraldine96