Just been searching on the Play.com website and found this.
Tron Legacy: Limited Collector's Edition (Play.com Exclusive) (Blu-ray)
Individually Numbered Uber-cool 'Cube' packaging
Tron: Legacy 1 disc Blu-ray with O-Ring Packaging
Tron Original Classic 1 disc Blu-ray with O-Ring Packaging
Daft Punk Tron Legacy Original Soundtrack CD
Exclusive Tron: Legacy Collectible art cards
Tron Betrayal - An Original Graphic Novel Prequel to Tron: Legacy
Play.com Exclusive Collectors Edition - limited to 1000 individually numbered units!
Retails for £69.99 and unlike the US version, this is limited to 1000 units. 99.99999% sure this will sell out, just like Avatar collector's edition of 1000 units.
Released date is the 18th April
Source