Sorry for double-posting (yes, I could edit my last post, but that wouldn't really reach you), I've just read some news on a german website, here's the translated version:
Google Translate
It basically says that a Microsoft website states, that the Surface Pro Lifecycle begins at 10th May, which could mean, that it will be sold somewhere around that date. They also mention a "reliable source" that stated pretty much the same. Considering all the other articles, this might not be too much of a rumour. I live in Germany, so that is pretty good news, I think Microsoft will probably launch it in UK, France and Germany at the same time.