Neil:
Welcome to Ireland Reaching Out!
The Caheragh RC parish records start in June 1818 http://registers.nli.ie/parishes/0024 I looked on www.irishgenealogy.ie for a baptismal record for Ellen and did not find one with a mother with a maiden name Coghlan/Caghlan. The only 1819 baptism for an Ellen Driscoll is below. Also if she was born in 1819 she would have been 13 or 14 when married in February 1833. This would have been technically possible with parental permission but not very common.I'm wondering if she was born earlier than June 1818?
www.irshgenealogy does have five baptismal records for John and Ellen's children which I assume you have.
Roger McDonnell
Area - CORK & ROSS (RC) , Parish/Church/Congregation - CAHARAGH
Baptism of ELLEN DRISCOLL of N/R on 14 September 1819
NameELLEN DRISCOLLDate of BirthN/R N/R N/RAddressN/RFatherTIM DRISCOLLMotherMARY CROWELY
Sponsor 1DENNIS DRISCOLLSponsor 2MAY MINIHANERecorded Diocesan AreaCORK & ROSSRecorded Parochial AreaCAHARAGH