Leaving aside the point that I don't really believe in "Celtic" music as a genre(remember a bit of Austrian repertoire, where the "Celts" came from..or not)..if you want to be a Scottish/Irish/ American band, great. But if you want to be Celtic, do have a listen to some stuff from Britanny, Cornwall,Isle of Man, Cumberland,Wales. All good Celtic places. And you might be agreeably surprised by some English material, the place with the most Celts of all ( after America, that is).