Tree Top Nets describes it best. Here's what they say:
Imagine giant trampolines, walkways, slides and tunnels all made from netting. Now picture this suspended up to 40ft off the ground in the tree canopy and you'll have the right idea.
This is a UK first and is designed to offer an amazing and adventurous way for both children and adults to play up high in the trees. Unlike traditional high ropes courses, you’ll be completely surrounded by 3m high walls of netting which means you are always safe and therefore you do not need harnesses.
You should know, that they only accept children 3 years old and older. As an adult, you're allowed to climb up there too and have fun with the kids.
Before you just drive over there, call ahead and make sure they have room for you. They recommend that you make a reservation.