One thing I always do when flying in the pointy(sh) end is NOT to use the duvet. Been a while since I flew in F, but the Club one is way too warm for my liking. So I either go without or ask the crew if I can trade it for a WT+ blanket, which is just perfect for my needs. And I know some will go 'ewww' but going sockless (only when sitting, never when moving out) makes another big difference.

Unfortunately there's nothing more inconsistent than temperature on a plane. Besides some crews believing that warmth makes for a cozy and peaceful atmosphere, airflow inside a cabin can be extremely capricious. The ex BMI A321s with lie-flats were a typical example. The bulkhead between Club and Economy blocked a lot of the airflow and the first 2-3 rows of Y were roasting while the ones behind could be a lot colder.