Hi I live quite near mitcham. I've ridden the track on my 24" 24 seven slacker. Great fun! its massive compared to baddow, has proper start gates and is way better maintained. Its a regional standard bmx race track. The track is run quite strictly and often closed when it rains. It's fenced and gated so you can't just turn up and ride. They do have pay and play sessions as well as coached club sessions. During half term their are council subsidised classes for kids where they provide the equipment. My 8yr old son really enjoyed it. Check their Facebook page