You can buy a lot of things at Certified which is near Ling and Sons. You can bring your own beach chair at the Surf Club but the issue is not finding a chair. There are lots of chairs...its finding the area in which you want to sit during high season!
If you want to sit at the beach but away from the front of the beach, no problem, you can get space. It is the issue with sitting by the water that is the problem. The huts, well that is a totally different story.............