Hi Hamish,
I would get onto the planning department in the Council,if you are creating off road parking I think you will need planning permission, I could be wrong but I think that is correct ,just give them a ring,they are normally pretty helpful,if he comes out just ask him what he would do,they like to give information,and will then guide you through procedure,good luck, Ray
PS, I don't see that leasehold or Freehold is an issue,unless in the lease there is a clause about it.