Like someone else has mentioned you're more likely to find them in corner shops and in the discount stores like Home Bargains and B&M.
But in my opinion they're probably not readily available because they're just not very popular. Gummy Bears are a bit boring and bland compared to the other sweets available.
Growing up I'd sometimes get a 10p mix up from the corner shop after school and there's no way I'd have wasted a penny on a gummy bear when I could have gotten a giant strawberry, a ufo, a black jack, a fruit salad, a fried egg, or best of all a foam shrimp/banana.
Oh this is absolutely true, even limited to candy with gummy textures there are so many good options -- Trolli worms, Starburst gummies, Sour Patch, Nerds clusters, Mike & Ike, Sweetarts gummies.
The thing these all pretty much have in common is incorporating a more sour/acidic taste to varying degrees so that is probably a turn-off for some but it's hard to argue with the result being incredibly flavorful.
Also Haribo bears are available everywhere. This whole thread is very odd.
https://de.wikipedia.org/wiki/Haribo
However this German newspaper says something about dancing bears being seen animal abuse, and thus bad marketing:
https://rp-online.de/nrw/staedte/rhein-kreis/geliebt-und-gef...
(Google Translate is your friend, if you don't read German.)
https://www.spektrum.de/magazin/faszinierende-chemische-expe... suggests that they didn't just change the name, but also the recipe:
> The gummy bears were invented in 1922 by the Bonn entrepreneur Hans Riegel, who christened his creation »Dancing Bear«. It was not until 1960 that the colorful fellows were renamed »Goldbears«. The dancing bears were significantly softer than their successors: Instead of the gelatine used today, a mixture of animal proteins, they consisted mainly of the plant sap gum arabic, which contains various polysaccharides (multiple sugars). Numerous companies now produce gummy bears and other fruit gums in many variations.
(via Google Translate)
I'd be surprised if they didn't make studies and test groups
https://www.amazon.com/Albanese-Candy-Flavor-Gummi-Assorted/...
https://www.amazon.com/review/R2JGNJ5ZPJT4YC
(NSFW)
Another funny thing is that as a vegetarian I realized quite late that this is a meat product (gelantine). It remains the only "meat" I eat kind of regularly because, as mentioned somewhere, they are still the best.