From Studland take the B3351 through Corfe Castle and on towards Kimmeridge. Just before you drop down into the village, turn left up the private drive to Smedmore House.
IMPORTANT: The private drive for Smedmore is often not shown by SatNav.
Do not rely on Google maps or the AA.com as they will take you through Kingston and Encombe along a bridleway which is not accessible to vehicles.