I'd note that the 2008 Handbook and the Epic Compendium 2.0 (link to the last one:
http://www.taccmd.tacticalwargames.net/ ... 69&t=15716) is something a bit different again. I *think* they were made obsolete when the 2009 errata was incorporated into the PDF on GW's website, but I'm not certain.
I'm a bit confused myself sometimes, but I think this is correct:
- The current rules for playing the game is found in the updated rulebooks on the GW website. Both NetEA and EpicUK use these.
- The army lists in these books are considered outdated by many people, mostly because they have some glaring holes for minmaxing (cheap Warhounds for one thing). But overall they're decent enough, especially if the player isn't experienced enough to exploit them. They're also IIRC limited to two Space Marine lists, two Ork lists, one Imperial Guard list, one Eldar list and two Chaos lists.
- NetEA army lists are in the 2012 compendium, found in W_G's link
- EpicUK lists are found at
http://epic-uk.co.uk These are lists developed and tested by EpicUK organisers for use in their tournaments
- France also has their own lists, but I haven't looked at them
As long as you agree on what core rules to use, you should be able to field rulebook armies, NetEA Approved/Developmental lists and EpicUK lists against each other without any big problems.