You are going to find that kids eat different things here. And some can be very stubborn about what they do eat. That fact came as an utter disappointment to me when I thought I would share my very best (and very hoarded) American food products with a group of 10 teen girls at a sleepover, because I thought it would be cool to show them what a typical American slumber party was like. I mean, they all watch "Buffy" for goodness sake!
Wrong.
Tell me why any kid would choose bangers over American hotdogs. Or curl their noses in disgust over peanut butter and jelly ("jam" here, their "jelly" is our "Jello").
Your kids are different because they grew up eating this stuff. But I will wager they will "cross over to the dark side" simply because 1) they are more adaptable, 2) they are more peer-pressure-able and 3) they won't want to look different or out of place.
Now, to answer your question...
I buy "American-style Hotdogs" at Tesco and they are pretty close. But you may have a time finding them because they aren't with sausages and there usually only tends to be about one or two packs each time. And I have had to reach my hand in blindly to pull one pack out because it was tucked waaaaay in the back. At my store they are near the boxed multi-packs of Indian takeaways, under the couscous salad. BTW, the hot dog rolls are the best here. Far superior, but the dogs come in packs of four and the rolls come in packs of six...some traditions never change.
Bologna and turkey dogs...good luck. I'm not saying "no" only because someone may have their finger on a stronger pulse than I. I have found mortadella, so if you can convince the white spots are just cool decoration, you may have a substitute...at designer prices. Just keep them away from this web site:
http://qn.quotidiano.net/chan/food_wine:2322603:/2002/01/18:Peanut butter. You may find some in the "Forgeign foods" section. I seem to recall seeing Jif. I am a Skippy person myself, so my sister brought over a H U G E jar she picked up at Costco before she came to visit. You're actually welcome to have it; never opened and I don't go through it quickly, still using a jar I got a year ago. I think she did it as more a joke...it
is huge.
Don't expect to find grape anything (being replaced by black currents, and is hardly a subsititute). There certainly isn't grape jelly (nor my fave, apple). You will find cans of grape pop/soda in Caribbean shops (we have a Jamaican take-away here in town). They do have a white grape juice in grocery stores, but...the flavor seems off to me, not the same.
Popcorn, no problem, even the salty microwave stuff. You'll find the popcorn of choice here is sugared (sweet) so be sure to read the label. No specialty "movietime" or extra-butter stuff, though.
Marshmellows, I've seen the mini ones, but not the big ones. No Tupperware brand, but products doing the same stuff, yes. Not Ziplock brand, not with the closure mechanism that slides across, but yes those pinch/pull ones that seal shut.
Having said all this...these are the comments I make for general grocery shopping. All is not lost
There are some mail order places that specialize in American products and carry the items in the brands you've mentioned. Leah has excellent links from this site. I happen to live in the town where one mail order place has a "showroom", Made in America, so for me, it's a walk into town (not open on weekends). The stock sometimes rotates, so if you don't see it now, if could be next week.
You will be happy to learn that McDonald's, Burger King and KFC are all over the place (and Subway getting there too).
Sainsbury's has outdone itself by offering a kid's line of products called "Parrot". If your kids are teens, they probably won't be pulled. It's the packaging they've done to make foods-good-for-you look fun.
I will add a personal feeling that may give you some comfort. Others are welcome to disagree because I have no scientific proof of this. I believe the food here is healthier, especially the prepared foods. Not an enormous amount of additives. Not a lot of preservatives. Local butchers are everywhere for the freshest of natural meats. Many people grow their own fruits and vegies and sell surplus on the side of the road. Organic farming is big here, as well as free-range. I'd say this country is a great place to feed kids, and maybe American products should be phased out for them. A good friend of mine worked at Oscar Meyer and to this day she will not even touch a hot dog ("You don't want to know what goes in to them!").
Food for thought.