We have driven past the chateau at Boussay many times, and have often stood at the gates and taken photos of the facade. The gardens are open to the public, but being very mild mannered and not completely sure of the etiquette we have never ventured in.
Last year we attended a hunting horn (Trompe - or Trompette - de Chasse) concert in the grounds of the chateau, which gave us an opportunity to wander around the gardens and get some different views of the chateau itself. These were taken in near darkness, late on a beautiful July evening.
The Chateau has an interesting history, having been founded by the Barons de Preuilly (who built the Chateau du Lion overlooking Preuilly) in the 11th Century. The Chateau is still owned and lived in by descendants of the founding family (a concept that staggers me). Because it has always been lived in it has never been restored, but rather remodelled and updated regularly, with constant maintenance in between.
The owners have written an interesting web page about the chateau, so instead of repeating and recycling, I will point you to in its direction - here (in French) or here (translated by Google into English) depending on your needs.