Both dates are saying the same thing.
The exchange is offering FTTC on some cabinets in the area, they don't enable them all usually, and the ones they do arrive in stages.
The 31st December/Jan 2013 date is a place holder, i.e. they will try to get the cabinet enabled, but no firm date has been set. So DO NOT assume you will have it in January 2013, it may slip to March 2013.
Key is to see what progress is happening to your local cabinet.