The British version of SONGS OF THE DYING EARTH is now available for preorder from Amazon UK at http://www.amazon.co.uk/Songs-Dying-Earth-George-Martin/dp/product-description/0007277482
The stories, of course, will be exactly the same in all editions. Only the Subterranean Press editions will include Tom Kidd's interior illustrations, however.
Whichever version you buy, Gardner Dozois and I hope you will enjoy the read.