Audrey,
One suggestion may be Bashley Park in Hampshire.
It is on the edge of the New Forest and not too far from Bournemouth. One advantage of this site is that there is a daily coach service to/from Bournemouth so you dont have to take the car. Also it is only a mile walk to New Milton where you can catch the train into Bournemouth and other destinations.
Peak season you may be glad of that option!!
Bashley is a clean site with good pitches and full entertainment etc and good indoor/outdoor pools, however when they say leave at 10 on departure day they mean it!!
Sandy Balls is another possibility but that is about 18 miles inland from the Hants/Dorset Coast and you may find they are already fully booked.