I spent a few days with my daughter in a rented house in Poole Dorset. Whilst there we visited Sandbanks, superb beach, good for swimming, there are good reasons why property on Sandbanks is some of the most expensive in the UK.
Can recommend a short break in the area, if you do go Rick Steins restaurant is well worth a visit, superb sea food, excellent service and fantastic views from the restaurant across the bay with all sorts of activities, such as kite surfing, to see.