This list from the UK contains a fair number of books not currently available in the US. The Quantum Thief by Hannu Rajaniemi is the highest ranked UK-only I came across, to be released in May in the US. Overall, my impression is that fewer are available as ebooks in the UK than would be the case in the US for recent releases.
I could not find Splinter by Adam Roberts as a legal ebook, but searching for it uncovered
The Dragon with the Girl Tattoo, by Adam Roberts, which I had to buy on the title alone. Only available in the UK unfortunately.