There are some windsurfing activities in HK. But normally I don’t find HK is a windy place. I haven’t seen any kitesurfers. I have found a link to show you some places. The place on Lantau is far away from HK Islands. I gues it will take 1 hour to go there.
Take the MTR train to Tung Chung Station and the bus NO. 11 from Tung Chung Station. When you see the coast line (the road is like a T and the bus turns to the left) it’s time to get of. On your right hand side you wil find the beach. http://www.windfanshk.com/center/site.html Have a nice time in HK.