Seeking Parish records for McCooke family: Errigal, Garvagh, Derry. Also Desertoghill, Garvagh, Derry.Thomas McCooke & Nancy McCooke (nee Brown)
You haven’t said what denomination(s) you are interested in. The RC parish records are on-line free on the National Library site:
https://www.nli.ie/en/family-history-introduction.aspx
For other denominations, there are copies of most parish records in PRONI, the public record office, in Belfast. Their copies are not on-line and so a personal visit is required to access them. If you are unable to go there yourself, you may need to employ a researcher.
http://www.proni.gov.uk/guide_to_church_records.pdf