In April or May, 2018, I am planning a two week trip to Normandy and Ireland, one week each. What is the best way to get from Normandy to Ireland? Thank you.
Fly from Rennes or Paris (direct) to Dublin
Or, if you want to make more of an adventure of it, go by overnight ferry:
Cork Roscoff - Brittany Ferries
Dublin Cherbourg - Irish Ferries
Rosslare Roscoff - Irish Ferries
Rosslare Cherbourg - Irish Ferries or Stena Line
For Irish ferries see here: https://www.irishferries.com/ie-en/to-france-from-ireland/
For a booking site covering all three companies: https://www.directferries.ie/ferries_from_ireland_to_france.htm