There's a small zoo type animal centre about 30 minutes drive away that we visit quite often and DS (going to be 9) loves. They do party packages (look round zoo, animal handling and picnic), which look good, but I'm not sure if the distance will put off some of the school friends parent. Would you take your kid that far or make an excuse not to go?
(Not sure if this is relevant, but to avoid a potential drip feed, DS and majority of the potential guests have SEND)