The Football Manager 2013 release date has been set: 2nd November. But you can play two weeks earlier if you pre-order the game.
Do that either digitally or at a shop and you'll get access to a single-player beta version of the game "around" 14 days before release.
Make sure the shop is taking part in the deal.
The beta version of Football Manager 2013 has "most" of the game's features, including the new Classic (light) mode and Challenges.
This beta version will disappear on 5th November, but you can continue with your saved game in Football Manager 2013 - the saves carry across.