There are actually two movies: the 1993 Hopkins/Winger movie and the earlier 1985 BBC version. They're both based, more or less, on a play that someone wrote about Jack & Joy's relationship. My friend Sheldon Vanauken didn't like the 1993 movie as much as the BBC production, because it downplayed Lewis' faith more, as well as almost completely eliminating the miraculous element to Joy Davidman's recovery. (It also based much of its theme on the absurd premise that Lewis was an ivory-tower theorist who lectured on human suffering but knew nothing of it firsthand. This about a man who lost his mother as a child, was mercilessly bullied at school, fought in the trenches in WWI, and spent much of his adult life being ordered about by a tyrannical old woman.)
I don't know about you, but I whistled up Netflix, searched "Shadowlands", and pulled up both DVDs. I'd recommend the BBC version first, though there's no denying Hopkins and Winger are both excellent.