As to training, so much depends on the father's experience with firearms. Seriously, knowing that would help.
If he's lived in the UK all his life he'd most likely have very limited experience with firearms unless he was an armed police officer (pretty uncommon) or had been in the military.
He also may have been a hunter (shotguns mostly) or been in a shooting club with what few types of firearms are still allowed. (Some rifles and black powder handguns, if I understand correctly).
What I'm saying is the average adult in the UK just doesn't have that much opportunity to learn about firearms in a practical way unless they are in the military or spend time in another country like the U.S. Even if he did visit the U.S. and did some shooting there, that wouldn't make him an expert and especially an expert at instructing others.
I'm going to quote Slhuang here to give my take on some of the things he says.
If it's for self-defense purposes, he would also probably be teaching them how to carry and draw from a holster. Drawing and reholstering is actually nontrivial, because of the muzzle safety -- a lot of people cross themselves with their own guns when they're first learning to draw/reholster.
I agree that drawing from a holster is something that should be taught and learned. But, what experience would he actually have to learn the RIGHT way to draw from a holster so he can teach it to his kids? If he hasn't actually trained in how to do it formally, it's probably something he wouldn't even think about teaching them as he wouldn't realize the importance.
This he could get from a book, the web, or whatever previous experience he has. He would must likely stress things like "Don't point that gun at anyone you don't want to shoot," and "Keep your finger off the trigger so you don't shoot yourself by accident."
If he had more formalized safety training, like military or police, then he'd model his lessons on their rules. Again, let me know.
2 - Loading/clearing (and the vocabulary of the weapon and its ammunition as he's teaching them this)
At the very least he'd go over the basics of loading the cartridges (ammo) into the magazine, how to load the magazine into the firearm, and how to work the action (rack the slide) on an auto-pistol to get it ready to fire. If the weapon has a manual safety (some don't, like Glocks) then he'd show them were it was and how to operate it.
"Ok, now that you racked the slide the gun is loaded and ready to fire. It's dangerous like that, so move the safety this way to put it on "safe." When you want to shoot push it the other way and pull the trigger."
Operating a revolver is even easier. "Push the cylinder release here forward and pop the cylinder to the side with your other hand. Here, now load the bullets (cartridges, but many people call them "bullets") into the chambers like this. Ok, now close the cylinder. There's no safety, so it's ready to fire. Just pull the trigger. (BANG! Etc) "Ok, now to reload push that cylinder release again and open the cylinder. Now point the muzzle at the sky and hit that ejector rod, this one here, yeah, push it down with your finger hard and that will eject the empties."
3 - Stance/aiming -- he would probably work with them bringing the gun up and firing rather than teaching them analytical accuracy
4 - Drawing/reholstering with a cold (empty) weapon until they have it (drawing and clicking the safety off (if a semiauto) in a smooth motion is something most people have to practice)
Again, unless he is a firearms instructor or an experienced handgun shooter, he's not going to consider the importance of teaching this or even have the skills to do it. He very likely may have them practice with an unloaded pistol, but if he's untrained he'd work on "getting it out of the holster quickly" more than anything.
5 - Drawing and firing, reloading (reloading may or may not have emphasis depending on the danger, which you haven't really specified . . . most RL gun discharges involve very few rounds, but for, say, zombies it would be very important for them to be speedy at reloading)
At a minimum he'd show them how to unload and reload the gun, assuming they have more than one magazine of ammo.
6 - Moving with the weapon (since it's for tactical/self-defense reasons) -- targeting and firing while moving without endangering their surroundings
7 - Drawing and firing quickly and smoothly and SAFELY while on the move (basically, all of the above combined).
This is ideal, and if he has the skills himself, and the time to spend, he would want to cover it. But, if he doesn't have the background, he wouldn't know how to do it.
And then cleaning and caring for the weapons afterward.
Not important in the scenario you described. This isn't NRA Basic Pistol. This is "Let me show you how to use this in case we're attacked tonight."
If I'm forgetting anything I'm sure others will weigh in . . .
That was quite thorough. The thing is, if he's not a pro with firearms, or very experience, he may not have the skills to teach all that. There's also the fact that time is limited.
I think it might go something more like this:
"Ok, I got a couple of guns from some people I know. Let me show you how this works."
"This is a Glock pistol. Push this button here, behind the trigger guard to release the magazine. There, now pull it out, catch it, don't drop it! Ok, the mags out, but it might still be loaded if there's one (a live round) in the chamber. Pull back on the slide like this" (works the slide). There, you see how that cartridge flew out? It was loaded. Now pull back again and hold it open and look at the chamber. Ok, it's empty.
Keep holding it open. See that little lever, there, under the slide? Push that up while you hold the slide back. That's the slide release. With it pushed up like that it will hold the slide open. See? Ok, no push it down (SNAP!). See how the slide went forward? That's how you can load it."
Ok, take the magazine and shove it in the bottom there. All the way up the mag well, hard. Now pull back on the slide and let go (SNAP!) Ok, that loaded a round in the chamber so it's ready to fire. Now, remove the mag again, yeah that button, and pull the slide back. Check the chamber. It's unloaded again."
When you shoot hold it like this, in two hands if you can, and look through this rear sight here. Line up the top of the notch in the rear sight with the top of the front sight. That's called sight alignment. Once you have the sights lined up put 'em where you want the bullet to go. Look, aim at the clock. See the front sight through the rear sight? Ok, that's your sight picture.
Now pull the trigger, gently, gently. (click). Ok, that would have fired if it was loaded. Try not to move the gun off target as you pull the trigger. Let's do it again."
You get the idea... Much less formal than a NRA class and focusing on just the basics of how to get the gun to work step by step.
