http://www.carsinthepark.org.uk/
While there is no official mkivsupra.net presence at this event we did have a fair few members show up.
It's a lovely venue in a lush valley, yards from a river. If you get bored of the cars you can visit Bolton Abbey or just go for a walk. A long walk if you happen to be me.
IIRC entry to the park was about a fiver.