Hi Chris
Your first port of call will be an examination of civil records at
www.irishgenealogy.ie .
In theory, in Ireland, all births, deaths and marriages were subject to civil registration from 1 January 1864 (non-Catholic marriages from 1 April 1845) and the ‘historic’ records, i.e. births over 100 years old, marriages over 75 years, and deaths over 50 years, are now searchable online, free of charge, at
www.irishgenealogy.ie. So you can search here for civil birth records (i.e. birth certificate) of John Lynch born 1867 and Ellen Roche born 1868.
On searching index, which returns name, event type, year and name of Superintendent Registrar’s District, a pdf of the full register page in which that birth, marriage or death certificate appears can be downloaded by selecting ‘image’. At present, images are available for Births 1864-1916, Marriages 1870-1941 and Deaths 1878-1966.