Nice dry feet
If it’s going to be wet, often overlooked is the importance of keeping your feet dry. Take more footwear than you think you will need, even a pair of walking boots can let water in eventually if constantly walking in long wet grass.
Take a pair of slippers or dry comfortable shoes for the evening inside the tent and always take lots more socks than you think you’ll need… including that thick winter pair that you weren’t going to take.
For a holiday luxury buy yourself a nice new pack of socks and peel off a new pair every time you need one. It’s difficult to be warm and happy with cold wet feet.