The weather in Holland is no different from the the UK, ie you take pot luck even it August. Don't let that put you off tho. The North sea beaches are excellent & there are plenty of inland lakeside beaches as well.
The campsites are clean & most Dutch will speak to you in English. All good stuff.
------------- I am, therefore I camp....
Don't forget to leave a review of the French and other European campsites you have visited!
The beach at Scheveningen is very nice - well worth a visit, can be windy as others have said. Lovely cafe's etc. along the promenade. Pier is worth a visit. From the tourist site...
Scheveningen has been a well-known tourist destination for more than a century. At the turn of the last century, people from far and away would travel to the sea for health reasons and cures Over the last few years, however, Scheveningen has undergone extensive renovations, including the development of new facilities along the promenade, a casino, theater, a mega-cinema, a Pier and indoor shopping center. Scheveningen boasts excellent accessibility and is only 10 minutes away from The Hague.
There are lovely sandy beaches all along the west coast but the islands across the top are truly amazing. Two of the islands are called Ameland and Nes. Can't recommend any campsites in particular. Wasn't really in a camping phase of my life when I lived in the Netherlands.