I've been wondering the same thing. The worst thing about Blu-ray is that it's not completely region free, I would have loved to import the Japanese version of Advent Children Complete to get the Final Fantasy XIII demo.
There is no region 2 in Blu-ray. It doesn't use a numbered region system, it uses letters (and the UK is B). As for the disc, as with most Sony releases it's region free, as is the US release. If it bothers you that much you can just buy the US disc for the demo. Do you people also pay to see films for trailers and walk out before the main feature starts?