I've been focusing on American atomic-age horror films (with an occasional Japanese reference) because that's what I grew up on. However, I can think of at least one British example of the genre: the Quartermass films and serials.
Professor Bernard Quatermass is a scientist-hero, not as rugged as the typical American equivalent, but that's just because British sci-fi is usually more cerebral. He's the main character of several television serials I've only seen stills of; these were adapted into Hammer Horror films, of which I've only seen one* (Quartermass and the Pit, which I saw under the title Five Million Years to Earth.) From what little I've seen, it meets all the same criteria as America atomic-age horror: mixed feelings about science, hints of paranoia, anxiety about the future. It's perhaps more pessimistic and less forgiving of military force than American films, but maybe that's just Hammer's take.
* I may have seen The Quartermass Xperiment/The Creeping Unknown, but I may be thinking of a Christopher Lee movie instead.
I'd love to see the original TV versions, but don't know if they're available, or if they are better, worse, or about the same in comparison to the Hammer film versions. Has anyone seen both versions of one of the stories? What's your opinion?