Irish helicopters have a pad just a mile from Rosslare off the main wexford road if you wanted to top up before you go, by prior arrangement. Its used for the lighthouse releif chopper.
From rosslare I think you steer 125 degrees and that will take you past tuskar rock for the welsh coast, and then as someone already said haverofrdwest would be the soonest after coasting in, approx 15 or so miles inland.