Things have changed in the last few years.
It has always been assumed that your fully comp insurance would be null and void on the 'ring, regardless of whether it was explicitly excluded by your insurer, but it's also been assumed that, as it's a legal requirement on any public road, third-party cover would be valid, thus protecting you against claims against you.
AIUI, this has been put to the test recently and it's transpired that the third-party cover isn't a given after all. As Fox says, the insurer is still legally obliged to pay out but there's nothing to stop them pursuing you for the money and they often will.
I'm not sure if actual legal precedent has been established on this but there's now enough doubt to make you think very hard. If you write off someone's Ferrari or, worse still, seriously injure or kill someone, you could find yourself personally liable for the costs, which could run into seven figures.
A lot will depend on the figures involved. If you have a light smack and there's a relatively small claim against you from the third party, your insurer may just pay it and let it go. OTOH, if you end up with a six or seven figure claim for killing someone, do you really think the insurer is just going to pay it and let it go?
There's been a lot of discussion on this on the 'ring forums and a lot of hitherto regular visitors are re-evaluating as a result of it. It also appears that this is a curiously British phenomenon, and German insurers have no problems covering you for third-party claims there, resulting in some people with dedicated track cars investigating how they can register a car over there and thus insure it on a German policy.
As for UK track days, as I've never participated in one I don't know for sure, but I've heard that the insurance works entirely differently. Your normal policy is worth squat as it's a private road, but you can obviously take out dedicated track day insurance. From what I've been told, this operates on a "no blame" system where no one can claim off a third-party for anything. Your insurance covers you for your own claims and nothing else. If someone else writes off your car and it's entirely their fault, if you don't have insurance then you're screwed. This is all hearsay so I could be totally wrong here
