Another one to add. On Thursday 16th March it's the official opening of the season at Donington Park for the BTCC Media Day.
The morning is taken up with photo shoots and announcements and stuff, then it's a 4 hour test session with all the teams in the afternoon, including free paddock access.
I've been for the last few years and it's usually awesome. Well recommended
Sadly won't be going this year but would recommend it to anyone who fancies seeing the cars (and an awesome track) with some great access to the cars and drivers. Not sure if it will be the same this year but usually you get a half price voucher for the museum on the back of the ticket. If you haven't been to the museum at Donny yet and like awesome Grand Prix cars then I would whole heartedly recommend that too!
5th and 6th of July, the Official Dunlop tyre test @ Snetterton. Free entry and a great day out, as teams and drivers are relaxed and willing to chat to anybody. Full grid take up. Full access as well. If you ask the marshalls nicely (beginning of the pitlane) you will get to stand on the pitwall, and really "feel" them go past, but age and number restrictions apply.
12th July - Official Ginetta Supercup Testing @ Snetterton - Same as the BTCC - I am going this one
I cannot make the BTCC testing (for the first time in 3yrs) as I am already away with work