The closest American accent to colonial England is American Southern, actually. We still say reckon, yonder, and britches (breeches), just like Shakespeare did! Yet somehow people think of our accent as being one of the least intelligent in the US.
I'm 100% against Ireland as a Civ. Ireland never had an empire ... has that whole little island ever even been united under one ruler? I mean, besides being part of the British empire? The Irish never built anything that could be considered a Wonder of the World. I'm having a hard time thinking of what Civ calls Great People from Ireland -- keeping in mind that St. Patrick was British. I'll give them a Great Artist or two: Joyce and Yeats. Other than that, I can't imagine why anyone would consider Ireland one of history's great civilizations, unless he's an ethnocentric Irishman.
AFTER they add Poland, Italy, Maori, Denmark, Polynesian, Magyar, the Iroquois, the Sioux, the Carib, Mexico, Australia, Afghanistan, and Brazil, THEN maybe it would be appropriate to stick Ireland in.