Permit an interuption from a surveyor.
The curtilage of a property is not the land around it in the same ownership. There are many examples of legal/planning matters/tax where the property is allowed a certain area to with as it pleases and beyond that use is limited.
An example might be a house in green belt where the council drew an imaginary boundary in the garden between an area near the house where they could build a barbeque, erect a trampoline or a children's play area and an area where they could not. The two areas looked identical and the overall area was perfectly reasonable for a house of it's size.
For tax purposes, selling your principal private residence is free from CGT only if the curtilage is less than about one acre. Anything more is taxed.
So a question of fact and degree as to curtilage....
You need a planning consultant or specialist lawyer Joel.