Amazon.com currently have a great sale on Blu Rays. Many of the titles, including new releases, work out a good bit cheaper than current UK prices, even with individual shipping factored in. Postage is £3.41 per disc individually. Might be beneficial to do it this way and avoid customs.
There are currently 116 titles, but there was around 130 this morning, so maybe stocks are limited. Many of the movies are region free but be sure to check for region locking before making a purchase. A couple of good pages for this:http://bluray.liesinc.net/http://www.thedvdforums.com/forums/showthread.php?t=478825