Your Trip to Cape Clear Island
Or if driving, catch the P&O ferry from Cairnryan to Larne or Liverpool to Dublin / Stenaline ferry from Fishguard to Rosslare, Cairnryan to Belfast or Holyhead to Dun Laoghaire / Dublin. The route is simple after disembarking from your ferry: If arriving in Larne, follow signs to: Belfast, then Dublin, then Cork, then Skibbereen, then Baltimore. Then the Cailinoir ferry over to the island. See below for links:
Ferries from UK
Ferries from Baltimore to Cape Clear
Visitors do not normally bring their cars over to the island although it is possible, by prior arrangement but this would be weather-permissible and is not economically viable for your island holiday.