I was told by a Marshall about 18 months ago when doing a Donnington PCGB trackday that Donnington have a number of noisy and quiet days per year and that they are monitored by the council, Donnington are therefore quite strict in enforcing the limits during the days.
I attended the weekend Gary W organised a few years ago at Llandow and can totally agree with Clive, a great weekend and very enjoyable trackday with as much time as you wanted due to the very limited numbers. Don't understand why the club should get upset as it was a similar day to how Blyton started and did not compete against the club.
Regarding trackday insurance I have only taken insurance out on a single day policy once with Insuremytrackday.com and that was in 2016 for a day at Blyton, at the time I had a Boxster GTS valued at £65K the cost was £475 with a £5k excess. I now always ensure I have cover within my annual policy which is really the only sensible way if you intend to do trackdays and feel the need for insurance. I use Mannings, own a GT4 and get annual cover including trackdays for not much more than the cost of the day in 2016. You do get conditions but most recognised organisations will get cover, my only issue has been doing a day at Prescott hill climb course which was not covered I just tried to be careful.
Hope the above helps a little