Hi Laurent,
How nice that you are planning a road trip in Ireland!
While France allows WW plates holders to drive abroad, all countries are not aware of these temporary license plates. I would stay on the safe side and wait to get your final plates & registration certificate if that's possible.
You can also get in touch with the
department of Transport who may give you a definitive answer. Did you already have a road-trip itinerary in mind?
A bientôt,
Antoine