First off, how old are your kids. Are they old enough where you feel comfortable teaching them gun safety? I'm a strong believer in gun safety at an early age, however that's your choice as a parent.

Next, having a family I would invest in a decent gun safe. Combinations are better oppose to a keypad in my opinion as far as deciphering the code. Or if money is tight gun locks work too.

This is just a couple suggestions from my POV, I'm sure you'll receive some more feedback on top of mine. Good luck, and what gun are you considering to purchase?

In addition to your safe, or if you can't get one right away, I would highly recommend this product:
Visualock 9mm
it is great because no matter who picks up the gun (you or your wife, maybe to move it) will know instantly if it is safe. Granted you should never become lax when it comes to safety checking your pistol every time you handle it, but when this puppy is through the barrel there is no way that it is NOT safe (unless you install it wrong) I've heard stories of trigger locks failing to grip the frame of the gun and then being slid back into the trigger, allowing the gun to fire. the visual lock prevents any ammunition from entering the barrel, therefore the only way a gun will fire (equipped with the visual lock) is to be field stripped and a new barrel replaced in the gun (on an automatic, revolvers: there's no way that gun will be fired) and without the key, you WON'T get it off. good investment. wishing you happy carry days in the future!

Good morning and welcome. I have a toddler daughter so I can understand where you're coming from. Given the tone of your post, may I ask what kind of training you have for yourself? Instead of shopping for a gun, have you taken any classes? Even if you don't own one you can still learn more, take classes about how to use them, and how to keep them safely at home.

To answer your OP, my wife was supportive but we both agreed that we had to lock the firearm away. We're balancing home defense with preventing our child from getting her hands on the Glock without our knowledge.

Where to begin....

I was shooting by the age of 5-6 years of age. I was taught gun safety from day one. Here is the key when it comes to kids, in my opinion. You CANNOT teach them that guns are bad, or that they are these big mysterious items that are just simply never, ever to be messed with. All that is going to do is drive the children to "want" to mess with them. Keep in mind that while you may be the safest person in the world, and have made it so that your children have 0% chance of ever coming in contact with your firearm, your children will go other places, to other people's homes and there is a good chance that those other homes will have firearms. The parents at that home may not be as safe and diligent as you are and there is a good chance your children will come into contact by no fault of your own. IF your children are taught that firearms are not toys and that when handled improperly, they can be dangerous, the chances that they will not mess with that firearm are much greater. The NRA has firearm safety booklets for children, geared towards their mentality/maturity level.
NRA - Safety Information for Parents

Notice that the key items to teach your children are to;
STOP
Don't TOUCH
LEAVE the area
Tell an ADULT

No where in there does it say anything about guns being bad but if you can drill these things into your children, their chances of surviving an incident with a firearm will be greatly increased.
Eddie Eagle Fact Sheet - Frequently Asked Questions

As it relates to children, there are so many dangers out there that we as parents have to try and protect them from but we can't be there 24/7. We have to "teach" or children how to handle situations on their own. We have to learn the information ourselves and then pass that knowledge on to our children. Speaking to strangers, what to do if someone calls them over to help look for their puppy, or offers a piece of candy (kidnapping, etc..) how to handle bullies, drugs, alcohol etc.. Lots of dangers and the only way to deal with them all is to be honest and work with our children on an ongoing basis, at an age appropriate level. Age appropriate is something that you and your wife have to agree on but all I can say is that our children are being exposed to things much earlier than we were when we were young.

On the topic of locking firearms up, this is very important. Regardless of how much discussion you have with your children, you just simply cannot chance curiosity. Placing your firearm up high on a shelf in the closet isn't securing your firearm from children. Separating the ammo while still leaving the firearm in an accessible place is not securing your firearm. However, you have to weigh and measure the ability to obtain AND use the firearm when you need it against securing it from the children. It would really suck that if you needed it to PROTECT your children, you couldn't get to it or couldn't load it quickly enough before someone harmed your child, wife etc.. My children are 8 and 5. My son has been shooting with me for 2 years and I will be taking my daughter this year when she turns 6. I wear a firearm, around them everyday. They see it everyday. We talk about firearms and firearms safety on a regular basis. We have discussions about NOT telling other people about our firearms, or that I wear one. We discuss how it's not anyone else's business about our families firearms, etc.. I have tripled checked that my firearm was clear and there was no ammo available AT ALL for them to use and then left my firearm, holstered in a conspicuous place like the kitchen counter, etc.. I placed it in such a manner that I would know if it has been touched or moved even in the slightest and then left it there, waiting. Not hovering over them but literally walked away to test them. They have never touched it. I still don't leave my firearms unsecured around them though as I just won't chance it. This is also why I don't like safes that require a key. Keys have to be hidden. Children find hidden keys. It's just that simple. Using a safe that requires a key, to me, is no more safer than placing the firearm up high on a shelf or separating the ammo while leaving both accessible. The ability for a child to obtain the firearm is present. I know this because I found my Father's key when I was young. Luckily, I had been taught proper firearm handling and safety and I simply wanted to see the firearms, not play with them, or show them to my friends, etc.. Is there some off chance that one of my kids could potentially learn the finger combination to my safe, sure but the chances are much less likely in my opinion. The chances of them figuring out the dial combo on the big house safe is just as unlikely.

I'd also like to add that one of the most important factors in educating your children, is being educated yourself. For the most basic of Firearm training, I would start with an NRA Approved course. There are several different course that are put on by NRA instructors all over the country, so there is bound to be one near you and they are affordable. The course material is mandated so you should be getting the same information regardless of who delivers it. Obviously some may deliver it better than others.

From there, I would suggest to continue your training with firearms to more advanced courses like a CCW course, etc.. hosted and given by a qualified individual.