I realize this thread is stale (I always check these days since people/bots/AI seem to like to dredge up old stuff)...
When I tracked my car back in the early oughts (both autocross and track days), a lot of my fellow amateur “racers" talked about this, but the question was more about what happens if I wreck my car on the track? There are insurance concerns regarding the use of your automobile that insurance companies might not help you fix. As far as I know, all the folks who did damage were able to get claims processed. But, certain companies were discussed where the waters had been tested. I think Allstate was mentioned (not sure, and not shilling, I promise).
As for private health insurance and (most) risky pasttimes, I don’t think I’ve ever heard of a problem. I suppose it’s possible that your health insurance might get denied or jacked post-incident (not that I’ve heard of that), but if I were doing something particularly dangerous regularly I would certainly look into it.
@Chargeride your friend who keeps getting hurt… Is he covered with UK policy(s) or does he have to do something special? I realize you guys have a completely different system in UK than here (US)… Just curious. And, what is your own personal experience?