ChrisKH said:Actually the beaches off Kent and Essex are probably cleaner than most popular European ones.
My vote for a quiet beach which you can reach by car within an hour of London would go to Broadstairs in Kent. Assuming nothing much has changed in the last ten years, the beach is reached by steps/stairs (it's at the bottom of a cliff, hence the name) has golden sands, rock pools, great surf and little nooks and crannies to explore. No amusements. Little seaside shop. Ice cream vendors, that's it.It's a nice quiet family beach with one/two local pubs withing walking distance for lunch or a drink and lots of green grass at the top of the cliff (fenced off) for a picnic and to play ball games. Jumpers for goal posts. Marvellous.
Otherwise, Clacton, Walton on the Naze (nice pier) and Frinton (quieter) if you fancy a slightly longer journey.