Ideally, the fence should be constructed in a rubble-free flat surface. If you can put it up on a grassy one, then that would be better. Some parents also construct the fence indoors and put cushions on the floor, just to cover for any eventuality. You can source great frames at Morrow Outdoor Play Equipment Ireland, if you are in Northern or Southern Ireland.
Take a good look into what other parents or buyers have to say about the product before making your decision. This will give you a more honest glimpse onto the product so that you won't have to regret your decision.