I like the idea of having an area enclosed by hedging, with herms in niches all around the hedge, which would mark out the boundary between the park gardens and the farm annex. It would form a kind of nymphaeum as well. From my plans below, one can see where the hedges would go. At this stage they are planned to be planted in Prunus laurocerasus - a Laurel-type hedge (yes, thinking of you Millie), but a cultivar of Laurel which is not quite so poisonous (Laurel is quite toxic to animals, even prunings which have been lying about for months on end), thus not a good choice for a farm boundary. Yew and Leilandii are also good choices.
It would have a wooden gate in the middle of the hedge, with statues placed symmetrically around the hedge, with a vista over the gate to the farm, and would be another area which couples could choose from when deciding where to having their wedding ceremony.