It’s been years since I’ve read it, but Fred Hoyle’s October the First Is Too Late involved time travel, as I recall, and was a good story to boot. If I’m wrong, please correct me and remind me what it was about!
I’d wanted to read October the First is Too Late for years, ever since I saw an ad for it on the sf book club as a kid. When I finally did get hold of acopy, I was disappointed. It’s not exactly a time-travel novel – solar conditions effectively send different parts of the Earth to different epochs in time. People don’t do any traveling through time. It’s hand-waving stuff that doesn’t make a lot of sense and it lacks a human story. Hoyle was capable of much better – “The Black Cloud” is great Hard SF (although not time travel).
If I Never Get Back by Darryl Brock. Time travel, Irish revolutionaries and baseball… what could be better? 
How about Lest Darnkess Fall, by L. Sprague de Camp? An Archaeology/Classics grad student, visiting Rome, is inexplicably hurled back to the year 536 while walking across the Piazza della Minerva towards the Pantheon. Once he realizes and accepts what has happened, he goes to a money changer to exchange his lire for local money. The story having fortunately been written in the 1930s, before the worldwide debasement of coinage, he actually does have some real silver and copper which which to buy a few sesterces. Once settled in, he persuades a banker to lend him some capital which which he “invents” brandy, and becomes a successful distiller.
Then he gets mixed up in politics…
De Camp also wrote a novella based on the premise that the Norse efforts to explore and colonise North America had been successful, but I don’t remember what it was called. Wheels of Time, maybe?
Spectre, look up to my post #3.
I don’t recall any novella of his about Norse explorers. His “A Gun for Aristotle” (post #14) talks aboyut an alternate 20th Century in which the Indian nations still hold the land in North America, evidently haven driven off the Norse and others.