I don't think they will since there are lots of songs they would need the licensing for. Just like how you can't get all the movies from iTunes in the UK that you can in the US...
Yes, I really hope it comes to the UK soon too.
I think there were reports that it would be expanded to cover the UK and other European countries in early 2014.
Also, I'm wondering if its worth taking out an iTunes Match subscription prior to iTunes Radio launching here in the UK - at the current price of £21.99 - in case Apple raise the price when it debuts