IMHO, you havent got a leg to stand on.

Given that it was a shrub garden before, its HIGHLY unlikely that the deeds of your houses detail access by vehicle to that shrub garden.

Id start seriously buttering her up the right way if I were you.

If she wants to be a cunt, she'll wait till you are in your gravel with your car, then put some "decrotive" 1 tonne boulders on her property, and your car will be stuck there forever