Are you after a school or somewhere to ride the layout on your own bike?
Just been doing this, and found the sainsburys on the a10 near the test center had space, but that only worked for the low speed stuff. We looked around that business Park, there’s enough car parks that one should have space at some point
My sons just used stadium rider training @ IKEA carpark in N18 they were very helpful I paid for his CBT and they called him back FOC for some extra help on the road (should have been an extra £60.00). They couldn’t have been more helpful 020 8531 5678