Yes, I don't see of what possible importance laws or regulations about powder storage in the UK could be to any of us on this thread, since no one shows a location outside the US. I think if there were any such thing here in IL I would have heard of it, and we've got a $%^load of regulations in this state, believe me. Any sheet-metal locker should be fine. The important thing is the "cool, dry" part, and that the powders, primers, etc. should not be contained in anything that would enable pressure to build to the point where the storage container would become a bomb. Most household storage containers, cabinets, closets, etc., should be fine. I wouldn't store the stuff in a gun safe, though....
"Dear reader, suppose you are a member of Congress. Now, further suppose you are an idiot. But I repeat myself."
- Mark Twain