If you don't want to do the sun holidays offer you can try code 25DWS01. Up to 35% off, but it's off the full price so if they have their own sale on then the discount will appear much smaller. Supposedly gives at least 5% off the current website price.
The offer applies to Classic Tents, Safari Tents, Classic & Comfort and Premium and Premium Azure Mobile Homes. The offer excludes Premium Plus/Exclusive, Ultimate, Ultimate Plus mobile homes, Apartments, Chalets, Bungalows and Lodges. The following parcs are not included in the offer; CA011 – Camping Lanterna, CD012 – Cambrils Park, CD013 – Sanguli, HL012 – Duinrell, IA015 – Union Lido, IA022 – Marina di Venezia, RV012 –Les Prairies de la Mer, RV015 – Club Colombier.
You can also look at booking directly with the campsite or through other holiday providers. Allcamps is a good comparison site. But Eurocamp offer a discount on the ferry/tunnel when booking as a package so having to book that sperately may cancel out any savings (you can use Tesco clubcard points to book ferry/tunnel if you do book separately).