HOW FAR would you travel for really great smoked fish? The trip to visit Woodcock Smokery, over four hours southwest of Dublin, and its  celebrated founder, Sally Barnes, feels like a voyage to the end of the world: up a barely paved road to a lonely hillside with views of mountains and green meadows, a scant mile from the sea. It’s less a place one stops to grab a bite than the endpoint of a quest to meet a guru.