I have been reading elsewhere that general testing takes place every wednesday at Mallory Park.
Never been, but seen photos that include a wonderful arry of cars, most recently Abba Kogans collection of Matra sportscars and F1's and many other 70's and 80's F1's.
I cannot verify it but today I think may have a turnout of Grp c and historic touring cars.
So if your passing the area it may be worthwhile to pop in. Dont know if its free.