From Ewell bypass (A24) take A232, s.p. Sutton, then Sutton, Cheam at next roundabout.  After 3/4 mile at right hand bend and monument, turn left into The Avenue, go through the gates and the car park will be on the right.

NOTE: It’s a few inches outside ULEZ!!!  Approach from the south and you’ll be fine (not fined).