England couldn't afford to buy what she needed, and the U.S. Congress didn't want to give them lots of stuff for free...Lend-Lease was a way to get them the stuff they needed. Would it have been better for the U.S. if the Nazis had conquered England?
Charles Peters, author of Five Days in Philadelphia, about Wendell Willkie and the 1940 campaign, was on C-SPAN yesterday. He talked at one point about Willkie's post-election trip to England and how he helped persuade Congress to vote for Lend-Lease.
I don't disagree with your history. I remember that there was a lot of hostility towards England which might have been part isolationist and part payback for the Revolutionary War and the War of 1812.
But I also recall a passage in the wayback machine that FDR deliberately exacted a price from England for old destroyers. Britain had to give up something large for the ships.