Ulex would probably cope with that situation - otherwise, possibly Olearia, Elaeagnus varieties or Griselinia. None are particularly rapid growing, but not slow either.

How about sea buckthorn (Hippophae rhamnoides) or Tamarisk?

I don't think anything will grow in PURE sand. You'll need to add compost to whatever passes for soil in your garden or you'll just lose whatever you plant. I'd advise adding water retaining gel and slow release fertilizer too. Mix them into the surrounding "soil", especially at the bottom of the planting holes or trench.

I've seen tamarisk growing well on sand dunes in Sussex - don't know how it would fare further north. The sea buckthorn is very tough but in a very windy place it may not grow very tall. Round here blackthorn grows on the cliffs, but again it stays fairly low.

Here is a link to a nursery that specializes in seaside plants - they may advise you.

http://www.misterwhat.co.uk/company/913674-corseside-nursery-pembroke

The Scotch Rose or Burnet Rose, Rosa pimpinellifolia, is a very thorny native rose that makes an excellent dense thicket; it's a natural-born secure hedge and will grow in very sandy soil by the sea.

Beautiful idea Bulbaholic

Burnet roses grow on the cliffs round here - and make "cushions" all of 6 inches high. You might find they get severely pruned by the wind if it's very strong.

They must be lovely Beattie! Our blackthorn doesn't get much above a foot or so right on the cliff edge - it all depends on how exposed Gayem is doesn't it,and she doesn't say where she lives.