It is not often that I think that a film/movie is worth seeing before you have read the book but Atonement by Ian McEwan fits the bill.
Atonement is a story about love and war, about lies and about the class system in Britain. It is also a story about writing stories. As novels about war go, it is not the best that I have read. For that, I would suggest Pat Barker’s Regeneration trilogy or Sebastian Faulks’s Birdsong. For novels dealing with the class system, it is probably also not the best. But the characters are well-drawn and the story is well told. I don’t think you would be disappointed with this novel if it were selected by your book club but I would suggest that you make a point of seeing the movie also and see if you agree that it adds to your appreciation of the novel.