Hi Paul, welcome to the forum.
I know this area well from my younger years as it was the go-to outing from where we lived, but not from a launching aspect as I'd never ever consider it. There is a massive 9m tide range and depending on which end of the beach you are at low water it dries to mud for between 1Nm and 1.5Nm out from the sand. The Bristol Channel is not a nice piece of water for a small craft.
Only in the past few days I've commented on here an ideal way to suss out an area is to get Google sat image up and look for boat activity, if there isn't any consider why not. If you look at all the houses/caravans and parking areas down that long beach there's not a boat to be seen with very good reason.
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