Thanks for the comments guys,
A couple of updates on this image, with some of your kind advice used, some not

I really like the wet sand look of the first of these updates but the black pebbles look wrong, in the second the large pebbles look better but the wet beach is not as good. The foam in both has good and bad points.
After a while though you tend to get bored with endless renders of the same scene. I might carry on though a get the best aspects into one final. What do you think? any ideas for improvement?