Hi Simon,
I work in Rotterdam and live in the UK and Holland, so if there is anything specific I might be able to find out for you.
If you mean "Camping Koningshof" near Rijnsburg, then it's an excellent site - and convenient for Leiden, the Keukenhof gardens, and Amsterdam (go by train - or drive to one of the Amsterdam park and ride places).
Koningshof is under the same overall management as the equally popular Camping Delftsehout (on the outskirts of Delft), and the city of Delft is also worth a visit.
Anything more specific? Robert