The roughly 15 km (9 mile) stretch of Atlantic Coastline at Lacanau is considered by many to contain some of the best surfing in Europe. All this depends on the season, of course, but its reputation alone means that, during the summer months, you'll probably be dealing with a lot of tourists at particularly popular stretches of the beach. This can be good if you enjoy Lacanau nightlife, but not so good if you prefer isolation on the water.
The North and Central beaches tend to get the most traffic on a consistent basis (as they're most accessible), however you can usually find less congested waters by either huffing it south on foot or north to "Alexandre Beach" on a bike. Water temps top out right around 21 C (70 F) in the summer, so a shorty's probably all you'll need to stay warm. Beginners are cautioned that swells and tides can get pretty intense depending on where you decide to surf, so definitely scope out a spot that's right for your skill level. Pack your gear and drive in for the day, or choose a campsite for a weekend of top-notch French wave riding.