I always think I will or have forgotten something and it’s getting worse - I keep double checking everything and it drives my wife mad.
Also check you have :
FX, Cash , bank cards, glasses , any medicines you need, driving licence, GHIC card, phone and watch, any travel cards you may have in case you need to use public transport if something goes wrong with car/transport.
maybe some masks. Charging cables / adapters and home keys!!
I also take a copy of the holiday confirmation with booking ref number and payments made and excursions booked flight numbers and times etc
Hope you have a great trip -