At a minimum, it should be required background for any class in which Animal Farm or 1984 are taught. I'm quite serious.
Orwell's first-hand experiences in the Spanish Civil War, and the in-fighting on the Loyalist side, led him to form the views of the man who wrote the more famous works of fiction. However, those who read only Orwell's fiction tend to see only a condemnation of Communism (which is, at least in this country, too readily equated with socalism). They go away with a completely distorted view of the meaning of those stories, and of Orwell's perception on life.
Homage to Catalonia is the truth behind the fiction. Read it.