Britain is not, on paper, an obvious beach destination. The water is cold, the weather is unpredictable, and yet - on the right day, at the right tide - there are stretches of coastline here that rival anywhere in the world. Powder-white sand backed by machair grassland in the Outer Hebrides. Vast, empty dune systems in Norfolk that make you feel genuinely alone. Dramatic sea stacks off the Antrim coast, turquoise coves in Cornwall that look lifted from somewhere considerably further south. The secret, of course, is knowing where to go, and being prepared to get a little windswept getting there.