The 1994 "comedic farce" committed by Roland Emmerich is an expensive one-joke special EFX movie that goes nowhere and is best forgotten. Submitted for your approval is a "fan anime" that "tells the rest of the story." By the way, the reason that the 14th century English folk stayed "far from Britain" was the destruction of the star maps to Earth. I'd say that a Hollywood-sized reboot is in order, since the "backward people beat the high tech space-faring civilization"tale has happened. (At least once...so far.)
"The High Crusade" audio book