There's a tiresome amount of ignorance in the Uk about US gun laws and their effects. Go look for yourself, but a couple of points:
In California, one of the tightest states, you can't go and buy whatever gun you like, and then you can't take
any out of the house without permits etc. 21+ not 18+.
Effect: Gun deaths in Ca are around half the average state pro rata/popn, and a third of the max (Alaska).
Currently you can't own an AR in Ca, but that's been challenged and is currently under appeal. Gun deaths are rising fast (+40ish% in a year iirc) in Ca (without any legislation change, iigir).
You can have say a pistol in your home, and I'm sure I'd have a couple.
Gun deaths in schools are a small proportion of the total, but emotive, so yes I'd support someone (or two) appointed in a school having a secured short and long -for use only by trained people.
A school I know of here, has tightened up a lot in the last 2 years. Back along, there was a door left open all day. There are controlled-only entries, and more cameras now.
I was at a practice by the Kenya wildlife service; in return for a donation I had a go with an AK74. Jumpy on full auto. "Only for noise" they said.
At 400yds from the ground on single I could hit a "crouching man" most of the time. They weren't all that much better than me.