Cumeenoole Strand, Eire
This is right at the end of the Dingle Peninsula in Ireland near to Ballyferriter and a few miles from Dingle Town.
The Blasket Islands dominate the scenery although there are wonderful views across to the Skellig rocks and the Ring of Kerry (see also here).
Porthcurno, Cornwall
This one of the nearest beaches to Land End in Cornwall near to the Minack Theatre. I like it because of the lovely white granite sand (although it's not much good for building sandcastles), but mainly because of its setting with the Logan rock and Treen headland (centre of picture) dominating the beach. This is an amazing headland to both view and climb and has wonderful views from the top - if you can get there!
Porthmeor, Cornwall
This is the largest of the beaches surrounding St. Ives in Cornwall. Unlike Porthcurno (above) it has wonderful sand for building sandcastles and all sorts of pools and fortifications.
Porthmeor is also excellent for surfing.
This is the furthest northwesterly beach on the British mainland. Good for camping nearby with lots of streams down to the beach. The water is freezing and you can't feel your feet after 10 minutes! Nearby is Smoo cave which is also worth a visit.
Featured in the end scenes from Shakespeare in Love.
Any beach in Australia
The beach to the right is Surfers' Paradise just south of Brisbane. The beach below is four mile beach and had no-one on it except us!