Aim for intersection of A52 / A38 and follow A38 (north). Take first exit (by Derby University) and continue along Kedleston Road towards Quarndon.
Derby train station is situated 5½ miles away from Kedleston Hall and Duffield train station is 3½ miles away.
Service from Derby to Ashbourne, calls at the Hall summer Saturdays only, otherwise alight the Smithy, 1 mile.
Free onsite parking & disabled parking.
http://www.nationaltrust.org.uk/kedleston-hall