Title: "There'll be bluebirds over the white cliffs of Do-Over"
Plot: Sent back in time before world war two. Works to help the allies conquer Germany. Interactions with major figures like Winston Churchill, General Marshal (item, he was unwilling to have the rank of Field Marshal because he did not want to be Marshal Marshal). Military, economic, political advice. Tell future Queen Elizabeth to avoid the Greek Prince Phillip. Set up a more robust French Resistance before the fall of France. Lots of opportunities: (reference Banadin's characters, the father and mother of Ricky Johnson.) Prevent the death of General Patton. Try do deemphasize strategic bombing, work for more infantry, less air force and airborne, better tanks. Might be an opportunity to assassinate Hitler before the war or get more Jews out of Europe. Warn about Pearl Harbor? Atomic Bomb? Prevent Russian Espionage or FDR's stroke?
Or perhaps efforts fail, where can hero go to live longer and prosper? The Cassandra problem, no one believes the prophet. There may be economic advantages to knowing about the coming war, even if can't be prevented or victory aided. Avoid being drafted. There may be several stories in this sort of approach. How to avoid the Depression? Stop Polio earlier? Avoid Vietnam?