PaddyAnne Just double check your eligibility before you spend too much time and money, I don’t think as a great grandchild it’s so easy.
I have cut and pasted the following;
If you or your parent were born on the island of Ireland before 2005, you are an Irish citizen. You can apply for an Irish passport without applying for citizenship.
If your Irish parent was born outside of Ireland, you will need to register via the Foreign Birth Registration.
If one of your grandparents was born in Ireland, but neither of your parents was born in Ireland, you may become an Irish citizen. You’ll need to have your birth registered in the Foreign Births Register.
If one of your great-grandparents was born in Ireland, but none of their descendants were, you can apply for fast-track naturalization after 3 years of residence.