What would we do it, OP?
I'd turn it into a place where parents of autistic?SEN children could come to rest. It would be fully staffed with physio, chefs and specialist staff to occupy their children with ocuupational/sppech/learning therapies whilst during the day the parents could do activities they wanted.
It would have a fully stacked library and a quiet cinema.
A swimming pool and steam room and self catering facilities.
Outside there would be nature trails and home grown vegetable plots for the children to get close to nature.
There would ba part where the children could be as loud and noisy as they want, but another wing where things were calmer and quiet.
At night time, there would be a glass dome in the garden and you could sleep out under it and look at the stars.
There would be wild swimming in the lake and an orchard for fruit trees with honeysuckle for the bees.
It would be a retreat.