We visited Weymouth, Dorset for a short break during the Royal Wedding 4 day weekend. The small town and its promenade is fantastic. It has sandy sections on the beach and they also had a kite festival. My 10 yr old loved the kite flying event on the beach. The backdrop to the beach is white cliffs around.
Close to Weymouth is Lulworth Cove and Durdle Door - most spectacular places on the south coast. The walks/treks in this area are just fabulous.
To add to this, we stayed at such a lovely cottage in Croyates (about 5 miles from Weymouth town centre). The Cottage had a huge garden and the owner of the cottage left us a lemon cake on the table which was the best lemon cake I have had so far.
The Cottage is called Barton Cottage and I booked it via Dorset Coastal Cottages website.