It really isn't terribly difficult. Lemme see if I can help.
Step 1 - the most important step. You need to get around to all the devices that all 4 of you will bring and check all - each and every - voltage specification plate on each and every charger/plug.
This is critical. Europe and the UK use voltage double or slightly more than double that used in North America. Your profile says "midwest". Can I assume that that means the Midwest of the United States?
Virtually all of the devices sold by Apple in the last few years are suitable for world voltage but some are only for the US, especially the older ones, and many third party chargers are for the US only, too.
The camera could go either way.
So, go around, take a magnifying lense with you and look on each charger block for writing (sometimes white on white or black on black) that will say something like Input Voltage 100-250 VAC 50/60Hz. If every one has that then each one can be used world wide and they only need a plug adapter like you have been using which changes the shape of the plug but does nothing for the type of electricity passing through it.
If, on the other hand, if any of them say something like Input 115vAC 60Hz you have a problem with that device and it will blow up or catch fire as soon as it is plugged in in Europe or the UK, usually with a suitably impressive show of smoke and sparks, and if you are very lucky, fire. You can't use that plug or charger or device in Europe or the UK without other precautions. If that is the case, please come back for special lesson "B".
For the porpoise of this post I shall assume that you have checked each and every device and are good to go.
Step 2 - get a few more adapters like you already use because they are easily lost and with so much e-stuff your kids won't want to wait while Mom hunts around for a replacement in the wilds of France or wherever when you can easily be the hero and pull a spare out of the luggage (you probably already know who it is that will lose the thing).
Step 3 - Get the dumbest, not protected, not illuminated, not smart, not spike resistant, not fancy; multi strip
or rubber cube. It has to be dumb because if you get one with any electronics in it at all the strip will blow up as above. It has to be dumb. Like one of the little rubber cubes you can get down at the Tru-Value for a dollar. It would be nice if it had all the bells and whistles and was dual voltage or world voltage and included all sorts of USB outputs and all, but you don't really need that and it will cost a lot more than a dollar.
Step 4 - when you arrive at your European or British destination, plug the adapter onto the stip or cube, plug that into the wall, and plug all the world-voltage capable e-stuff into the strip. VOILA!
You only need one (and spares) adapters because all the US plugs plug into a US shaped strip.
Remember, if any of them fail Step 1, please come back for level B help.
Footnote: Most things now use a world voltage USB plug adapter out of the box. You can plug a Nokia device into a plug adapter from Apple and vice versa, and so on. Except for a very few very power hungry devices like hard drives and DVD readers which need extra ooomph, USB is USB as far as power is concerned. So if some of the devices don't need to be charged every night they might be able to share a USB plug and make a bit less to carry...
Happy planning. When's the trip?