To get over to Cape Clear by air or road: you can find cheap fares from Ryanair Stanstead / Aerarann from Edinburgh both to Cork. From Cork airport, catch the bus to Cork city centre, then a bus to Skibereen, then to Baltimore.
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: