Yep, that's the main one AFAIK. Depends on tide and wind direction, but is reliably good when it's on. Nice park, shower and a field to set up in. Even a crapper.
I asked about Lake Ellesmere last time, and was told it was polluted badly -- but then they had a comp there....? Dunno.
Any beach on the Brighton side will do fine. Waves usually aren't big enough to be an issue, and there's flat water between them

North a bit, there's another estuary that's kiteable but the launch is a bit hairy. Massive waves over the other side of the spit too. I'd have to look at the maps to figure it out.