If you have half an hour spare, you can turn left, ice cream at Teddys ( just after People's Park) follow the coast road around Sandycove, Martello Tower (James Joyce), Coliemore, Bulloch Harbour, Vico Road (view to die for), Killiney Village, Military Road, then hard right for Ballybrack, and cut into the M50 at Cherrywood.
Just Yummy!