The website seems to have been updated now

http://ginetta.com/championship_tracks.php

31/03/2012 Brands Hatch Indy Junior & Supercup
07/04/2012 Oulton Park Challenge
14/04/2012 Donington Park Junior & Supercup
28/04/2012 Thruxton Junior & Supercup
09/06/2012 Oulton Park Junior & Supercup
09/06/2012 Rockingham Challenge
23/06/2012 Croft Junior & Supercup
23/06/2012 Brands Hatch GP Challenge
22/07/2012 Cadwell Park Challenge (Sunday only)
04/08/2012 Snetterton Challenge
11/08/2012 Snetterton Junior & Supercup
25/08/2012 Knockhill Junior & Supercup
08/09/2012 Silverstone 300 Challenge
22/09/2012 Rockingham Junior & Supercup
29/09/2012 Donington Park Challenge
06/10/2012 Silverstone Junior & Supercup
20/10/2012 Brands Hatch GP Junior & Supercup

Although the main page still says 2011 Calendars..