Ouch, glad that you're essentially in one piece though. Get better soon.
You done a reccy for CCTV, if you were near any government buildings they should have 7 days of footage.
[Edit]
From your description:
http://bit.ly/lBsNu8 is the view to the nearest CCTV camera, and about on the point that the accident happened. The camera should have caught it assuming little shrubbery growth and that the camera at the back of the building is on - but you'll struggle to see anything but the car colour. Depending on the lens on the cameras on the roundabout they should just stretch to the registration - most of those old beasts are very wide angle.
Give Custom House a call.