Here is a Cultural Literacy worksheet on the Battle of Britain. This is a half-page document with a reading of three relatively involved compound sentences and three comprehension questions. It explains the Battle well, and so is a good general introduction to this epochal event in World War II.
If you find typos in this document, I would appreciate a notification. And, as always, if you find this material useful in your practice, I would be grateful to hear what you think of it. I seek your peer review.