Looking for origins of McKernan clan who emigrated to England

Our McKernan clan emigrated from Ireland (parts unknown) to the Salford, Manchester region of England in the early 1800’s. My great great grandfather John McKernan emigrated and married his wife Julia Lanigan in England. We “guestimate” that John was born about 1800 – 1805 but we don’t know where in Ireland. Julia was born in Moyne, County Tipperary, near March of 1815. They were married in Manchester in 1838. My great grandfather, Peter McKernan was born in England 3 March 1846 and we have good records of the family from then on.

All our Genealogy studies originate with Peter in England but my father’s notes state that his “great grandparents were born in Ireland and emigrated to England”. My brother and I spent three weeks in southern Ireland but only found distant relatives (from Nenagh and Tipperary) on my grandmother’s side (Purcell). On that trip, I learned that the greatest concentrations of McKernans today are mostly found in northern Ireland (Counties Fermanagh and Armagh) so I suspect John may have been born in the north. My next trip to Ireland will be next year and I need to find where to go to look for records.

I am seeking any assistance I can get in Ireland on the McKernan family tree, starting in the 1800’s. Any help would be much appreciated. I can be contacted directly at lifeworks@oldsnet.ca . My name is Dennis McKernan and I live in Olds, Alberta, Canada.