The beach is massive, but land kiting is only permitted in a very small area with often dubious sand conditions. There are some great lagoons for kitesurfing at midtide. Again, there is a zone for kitesurfing, but it is PLENTY big enough.
The zoning at Brancaster is very important. You will be seen if you go out of the zones and you WILL piss off the locals, so please be aware of where you can go and where you can't. That said, I hope you have a banging session, it's a top beach, shame I don't live near it any more!