If beaches are your thing then you must visit Camber Sands, as it’s probably the best, most ‘beachy’ type of beach there is in England, with its vast expanse of proper holiday sand (as in the finely ground type, not shingle), heaps of sand dunes & a shop where you can buy 99 cones with flakes and all sorts of plastic you can use to fashion sand castles, forts, entire medieval towns….?
There are other beaches nearby at Winchelsea, Fairlight Cove & Pett Level which are much more rugged and cliff-like. Particularly fun if the weather’s choppy and on those days it may even be worth manufacturing a row when you get there as storming off against the backdrop of turbulent seas, lashing rain & giant waves beating against the cliffs will guarantee a memorable occasion.(NOTE: this is recommended for Winchelsea more so than the other two as it’s a bit of a long stomp all the way back to the Ship from Fairlight in particular…)