Dry area

you could either take a lot of the sand out and replace it with good soil.i suspect there is an underlying reasen it is so dry there so it is possible this idea wouldnt work unless you planted it up fully and quickly and mulched it.this still mite not work which could be a bit dishartening excuse my spelling.you could make it much much dryer and actualy grow cacti andi think there called suculents or and and i think this has the best possibility of working make a bog garden bye digging a lot of soil out .putting in a polythene with a few holes in and putting the dirt back.thatswhat i would do i think but without actualy seeing it its hard to see the reasen maybe and to what extent it`s dry .i hope this has bean helpfull.take care enjoy the sun bye for now

Rosemary and cistus immediately spring to mind chris as they come from the same place as lavenders. Also sedum spectabile with fleshy leaves. How cold are your winters? Salvia microphylla might make it

Have a look at http://www.rhs.org.uk/advice/profiles0803/gravel_garden.asp
Might give you more ideas to add to Andrew's excellent suggestions.

Because sandy soil is so free draining, cold winters might not be a problem. Whatever you plant, do your best to improve the soil adding plenty of compost to the planting hole and some blood fish and bone too. Mediterranean plants and grey leaved plants should do well and I would add salvias such as 'Caradonna' and 'Mainacht' plus the culinary variety, Santolina, ornamental grasses (many are drought tolerant) and maybe something like Eucalyptus if you have space, or cypress trees. You will undoubtedly get inspiration from Beth Chatto's dry garden. Good luck!