Arriving at the dunes is quite a site! Almost looks like you are on a different planet.
We hired 2 sandboards from "Have a Chat" general store... one was a stand up board and the other was a sitting one.The lady at the store was very friendly but the 'sitting' board did not slide at all and was very disappointing after climbing up the steep slopes repeatedly to try again. The 'standing' sandboard worked well and we had a great time using this board. I noticed a bus load of tourists who all had the sitting boards from "Have a Chat" store and none of their boards were sliding either.
It was very windy so I recommend bringing a jacket, the sand gets EVERYWHERE so wear glasses or goggles and maybe even a scarf around your nose and mouth!
Overall we had a great time and would definitely do it again if in the area. It's quite tiring climbing up so 2 hours should be plenty of time.More