Any of the sun lovers, and grasses. Conifers look particularly effective, too, and thrive in the heat reflected off the stone. Chance, too, to grow some rock garden plants which don't like soggy soil up round their necks, and the stones give their preferred conditions (so long as the ground underneath is well drained). Others might include dwarfer hebes (H. pinguifolia 'Pagei', H. 'Green Globe', parahebe, daphne retusa, and daphne petraea (look them up and ensure the soil is right for them), the neatest shrubby potentillas, like P. 'Red Ace'. Of the grasses I would use stipa tenuissima, anemanthele lessoniana (evergreen and bronzed in winter), molinia caerulea 'Variegata', hakonechloa macra 'Aureola', and pennisetum 'Red Buttons'.

A lot of irises do well in gravel with their rhyzomes above the gravel.

Chuck a pkt of Pancy seeds onto the gravel,
they'll grow and look very natural?

Also the hardy geranium's really do belong near gravel, they spread and take away any sharp lines of the likes of drives or paths,
they come up every year and look very relaxed and country
cottage garden look.

I would love to advise on semi-tropicals and mediterranean plants which are at home in the dry, gravel, garden but I'm afraid you don't say where you are in the UK. As the advice for (say) N.E. Scotland would be totally different from the advice for (say) S.W. England, I'll keep quiet until you amend your home page. Sorry, I'm not being awkward but it does make it very difficult when people just say 'UK' as their home area. A small country (ies) but huge climatic differences.

Winter flowering heathers absolutely love a full sun position in gravel

just iust side of market rasen Lincolnshire thats where i live im looking for that for the local climit

If you want an 'exotic' feature you will definitely be safe with any Phormium and should be OK with a green Cordyline. You may get away with a red or variegated one if you are willing to fleece it whenever a cold snap is forecast. I would stay away from most palms, expecially the ones sold by supermarkets as garden hardy. They are sometimes but only in the south west of UK. And remember, the bigger the plant, the hardier it gets so if you want to save money and buy a small one then keep it under glass for the first few winters.