In reply to jimtheape:
I don't want to piss on your parade, but I hope this installation is being planned properly. I'm in despair at the amount of intrusion of HSE into all walks of life these days, but the fact is that if this wall is being built for formal use by an organised group (scouts) rather than just for you and some mates to play on, there'll be all kinds of health, safety and insurance hoops to jump through.
I presume your group leader's been through all the requirements and has discussed it with the Scouts' insurers, etc? As I said, HSE is over-intrusive these days, but the reality is that as a scout group, I doubt very much that you'll just be able to bang a few holds onto a wall yourselves,and start climbing.