Hi Leagen,
The Church of Ireland is a 'province of the Anglican communion' in Ireland so not Roman Catholic. The Church of Ireland was the official church in Ireland until 1869. It is their registers which were destroyed in fire of 1922. Some still survive and are in the Representative Church Body Library in Dublin. Roman Catholic registers mostly remained with their parish church.
On the history question, Ireland did not gain independence from Britain until the 20th century, so in 1800 it was still very much ruled by Britain. An Irishman might belong to either church in the 19th century, but also he could have been Presbyterian, Quaker or Methodist. Given that you believe the origins of the family to be in County Cork, then I would say there was a fair chance of their being Catholic, especially since they left during the potato famine. That implies that they were the land workers, not the owners, who would more likely have been Anglican in religion.
I'm sure someone else can add more to the topic.
Nell
