Being curious, I took out my air law book.
"In order that an aircraft can legally get airborne, and land again, the 500 ft rule does not apply to aircraft taking-off and landing 'in accordance with normal aviation practice'".
"None of the Rule 5 provisions apply to an aircraft taking off, landing, or practicing approaches to land at a Government (military) aerodrome or a licensed aerodrome (again in accordance with 'normal aviation practice')"
"Practice approaches at an unlicensed airfield are subject to Rule 5 and so, for practical purposes, are prohibited." [...] "However, the CAA has in the past stated that an approach to an unlicensed airfield need not end in a landing if the approach is made to assess turbulence or crosswind, to inspect the surface condition, or to check for obstructions and slope." "However the 1000 ft provision should be considered as applying to aircraft taking off and landing at an unlicensed aerodrome."
So the way I see it: at a licensed aerodrome none of the low-flying rules apply as long as you apply "normal aviation practice". At an unlicensed aerodrome (or, I presume, a beach???) all the low-flying rules apply, except the 500 ft rule, provided that you are landing, taking off, or performing an approach to assess the conditions of the landing area.
You still need to have permission of the owner of the beach though.