The sand on Shifting Sands (and the recent diorama) is, suprise suprise, real sand. I obtained it from a freind in the ornamental masonry field, I believe it is the stuff used to repair cracks in sills and lintels etc.
Once the area was landscaped and track ballasted, I applied a coat of PVA where the sand was to be. A layer of sand was sieved over the area and tamped into place. As finger print marks were a risk a rubber glove is advised!
When the sand is sieved into place bits will land where the glue hasn't been applied, this is how I got the effect of it blending with the ballast. These areas are held in place with artist's matte medium (I get mine from Green Scene at exhibitions). I also go over the rest of the sand with the matt medium, this helps set it into place and gives it some depth.
After the sand is dry I dry brushed with MIG weathering powder 'beach sand', followed by the Silfor grass tufts. These were lightly weathered to remove the sheen and give some colour variation.
As for beach huts, they came from a painting purchased in a high street chain. This actually turned out to be a framed greetings card! This was scanned and overlayed on a real beach scene.
Hope that helps,