There's also the moonlight challenge this month (can't remember the date), it's 5/6 laps in Kent country side you can't do as much as you want and get a certificate, once you've gone pass 20 you get a medal. There hot food and drinks available after each lap as it ruddy cold.
There is a thread on here somewhere.
Is an excellent race which I intend doing next year, can't this as will be away.