If you are considering the Catalan part of France, it is only a quick hop across the border into Catalonia, Spain and prices are cheaper here.
The Costa Brava has many attractions, not just the beautiful rugged coastline with tiny coves, to big wide sandy beaches. It's natural marine parc off the coast of L'Estartit, castles and medieval villages are doted all over.
Take a look around the central area, which is nothing like the image many may conjure of Lloret de Mar!!!!
Calella de Palafrugell, Tamaria, Llafranc, Begur and it's beaches, L'Escala, L'Estartit etc.
These areas are where Spanish and Catalans holiday, and lots have second homes here, along with many French and other Europeans, but not too many Brits.
Camping/holiday parcs are very popular and not just for touring, but with ready erected tents to deluxe mobile homes and glamping.
I recommend El Delfin Verde which is situated directly on the beach between Torroella de Montgri and Pals and has been recently updated to include it's own water park:
www.eldelfinverde.com/en/
The site rents it's own units, but other Operators use it too including: Eurocamp, Vacansoleil, Suncamp, Lifestyle holidays and more.
Lifestyle tend to be the best on price and although it is very busy during school holidays the last week in August into September tend to be a bit quieter and cheaper.
From Dieppe the drive takes around 10 hours and some of the motorway is free. Avoid Paris by taking the route via Chartres, Orleans towards Clermont Ferrand, across the magnificent Millau bridge, through the Cevennes National Parc, passing Beziers and Perpignan before crossing the border into Spain.
I have travelled extensively in France and lived there for a while, but Catalonia beats the South of France IMO