I would be asking the insurance company what they will require not an internet group, even as knowledgeable as we are, ultimately it is them who will dictate if it meets their requirements and if they will pay out in the event of it all going horribly wrong, even for something minor like a bit falling of the projector and hitting one of the congregation on the back of the head, if they didn't know about it and haven't approved it they won't pay out. As others have said there are a number of regulations that this may or may not need to comply to depending on how it's to be used, and by whom, basically if it's a properly designed and engineered structure and installed in accordance with the manufacturer instructions, had a suitable signage displayed showing it's safe working loads and distribution and is periodically inspected in accordance with the manufacturer guidelines then will meet most current UK regulations. And to go back to one of the points in the original post that is not going to be a budget option or something you will find on eBay. Also consider the insurance company will probably want it inspected by one of the assessors annually at the churches expense, and that won't be as part of any regulations other than covering their arse, and the premium will probably be adjusted as well