the only time in november that's crowded is Thanksgiving Day weekend. Thanksgiving Day is the 4th Thursday of November, which this year falls on the 25th, the day after you're leaving, so you're ok.
If you're flying out on Wednesday directly to the UK, you won't have a problem. Thanksgiving Day is the highest air traffic day of the entire year in the US. Everyone celebrates turkey day and for every American expat i know, it's the day they most miss being back home. And you can count me in that group.