People will also have chance to use the libraries in Wightwick Manor, Wolverhampton, Powis Castle, Wales, Kingston Lacey, Dorset, and Upton House.
The charity also intends to take on operational management of Heartlands in Cornwall, subject to lease arrangements with the council.
Hilary McGrady, director general of the National Trust, said Battcock’s unrestricted donation would give the charity a “huge boost” to carry out “vital” work.
“We will work with other charities, organisations and authorities to try and make sure access to nature, beauty and history is a right for everyone, not a privilege for a few,” she added.