An important thing to point out is that, under a FIS at the moment, as a GA pilot I would normally get traffic information from the controller if he/she is not too busy.
Under the new system, if you want the controller to give you traffic information you must ask for a 'traffic' service. If it's a nice day and every man and his dog is flying, the controller will probably be too busy to provide a traffic service, and the most you will get is 'basic'.
With a basic service the controller is not allowed to give any traffic information, as the CAA do not want "blurring of the edges" when it comes to the different types of service.(unless the controller thinks there is a "definite risk of collision").
In other words, after March 12th, make sure we all keep a very good lookout!!
Maybe they chose this date so that the next day when it all goes pear-shaped, the CAA can blame it on the fact that it's Friday 13th!!!