There are only a few dedicated topless beaches around England.
True white sand is only found in parts of the world where there are no iron-bearing rocks around. Sand is mainly silicon oxides, which are white, but often also contains iron oxides, which give a brown or yellowish colour. There are a few English beaches which may look white from a distance, but turn out when close to look that way due to naturally occurring chalk dust being mixed in with the sand. There are near-white sand beaches on some Western Scottish islands but very few in England.
Some English beaches are composed of shingle or pebbles, due to being in locations where strong wave action washes away sand faster than it can accumulate, leaving heavier stony material behind.
Big sandy beaches requires the combination of a large tidal range, weak wave action with a long wavelength, and a shoreward prevailing wind which blows a lot of sand slightly inshore from the tide line.