Stanloi on Twitter mentions that you can pre-order the cd for £4.99 from HMV if you'd rather not import it from the US, but HMV is not offering downloads at this time.
As to the availability of the Social Network Sountrack on Amazons worldwide, for reasons beyond anyone's control at this point, unfortunately only Amazon US allows MP3 downloads. TSN will be available in the usual spread of online stores soon though.