I dont know of any specifically, but have you tried around the Hunter Valley? Quite a popular tourist destination so there might be a farm stay there. Or in the Southern Highlands perhaps (Mittagong, Moss Vale and other little towns in the area are also popular with tourists).
Or Mudgee. mostly a wine area now, but there may be a farm stay somewhere. I know there is one just down the road from my parent's sheep and cattle property, but I wouldnt recommend it, especially with a small bub.