My off-the-cuff US response is that I think you could use any of a number of words and they would all be acceptable. I don't see why you couldn't say "a scintilla of hope" or "a twinkle of hope" or "a ray of hope" or "a flash of hope." I don't perceive "glimmer of hope" as an unalterable stock phrase, idiom, or colocation.
The quick reality check for me is always a couple of searches: a site search of Project Gutenberg, followed by a Google Books search.
site:www.gutenberg.org "glimpse of hope"
One hit, from an 1871 British novel:
"And all unvisited by a ray of light, a glimpse of hope, even by the dream of what might be, which has gilded so many a weary night-watch with fleeting visions of the dawn."
books.google.com turns up thousands of hits but I don't know how relevant they all are. (Google is quite unreliable on searches for exact, literal phrases--it tries too hard to generalize your search for you). A few:
"Those on the cusp of adulthood provided a glimpse of hope for the future," a recent Yale University Press book about the end of the Holocaust.
"The Israeli-Palestinian peace process in the early 1990s offered a glimpse of hope also to the relations between Israel and its Arab citizens."
"However, when his cool reflections returned, he plainly perceived that his case was neither mended nor altered by Sophia's billet, unless to give him some little glimpse of hope, from her constancy, of some favourable accident hereafter."--Fielding, "Tom Jones" (Why didn't that turn up in my Gutenberg search?) (It's in the PG text). (Google is weird).
Oh, one of the funnier irrelevant search results: a book about (the famous US comedian) Bob Hope had a reference to somebody catching "a glimpse of Hope!"