1—As stupid as the gun laws have been, the British publicv has never owned guns en masse. The highest amount of legal guns was 1.6m in 1996, and most gunowners like myself owned more than one.
2—All major UK police forces have firearms units on constant standby, so your assertion re armoury=too late is a nonsense.
Go read The Sun. Several stories in it about cops having to go back to the armory or calling out special cops who are certified to carry guns. Don’t go making accusations until you know all the fact.