Camping in Lantau Island is not the best camping on earth, however, for a long weekend away from hectic city of Hong-Kong with easy access, it can be a good alternative.
We stayed at the Long Coast Cheung Sha http://www.longcoast.hk/engpage/, price was very good for Hong-Kong standards, 10 minutes by car to centre Lantau, with all city amneties such as supermaket, cinema, shopping and MTR to Hong-Kong.
The campsite offered nice tends, some would say even a 5 star camping, as they all have air-con (trust me, you are going to feel blessed), but as a surf destination? I would say it's overrated. Either I was very unlucky, or the waves during my stay were very flat - not higher than 20cm, and the water wasn't very clean too.
Although staff were very friendly, and helpful, you can do kayak, windsurf, skimming and the deal is, you pay for the water sports and they offer you your stay, which suited fine for us.
There are some restaurants along the beach, with Western and Asian food, and often you'll see private boats arriving at the beach and people going there just for lunch. It can get a bit too crowded sometimes.
If you have a chance, Sai Kung is a better choice for a stay as I was told. Bigger waves, and cleaner water, however, it will be wild camping.