you need to do it as a private trackday, where the ring is closed to the public. Then you can sometimes get insured, however for the cost of insurance versus buying another mk1 it may not be cost effective. i never bothered insuring the mk1, but insured the vx220 for 10k.
Richard Egger were the only ones i found to insure me at the ring, but i was already a road policy holder with them that also included 5 trackdays. they are great to deal with.
competition car insurance is another company who i am now with, as they also do 5 free trackday covers, but dont know if they cover the ring on private days.
Bookatrack.com are hoping to go to the ring again in 2012, so sign up to their website for newsletters as a reminder.
some insurers wont cover european trackday companies.