The nearest town to the campsite is Henfield, around two miles away, where you can find a supermarket, post office, major banks and several restaurants and fast-food outlets.
Henfield also lies along the South Downs Link, a unique walking/cycling route running between Shoreham Beach and Guildford. There is a cordoned children's play park in the centre of the main camping field, with several safe and fun amusements.
Kids will easily make new friends and run themselves out, allowing you to sit back and relax.
I have no direct experience of this site but it looks inviting and its guest book is full of promising comments.
If you simply want a fun weekend away from the big city, then our part of Sussex, just north of Brighton, is easy to get to, by rail or car.