Even when I am going to mainland Europe I don't pre-book campsites. I book a ferry passage between 1 and 3 weeks before departure. This allows me to be flexible. If I particularly like the campsite I can stay longer. If it is not so enticing I can move on. This is precisely what happened when I went to Luxembourg and Switzerland last summer. I booked the ferry only a couple of weeks before I set off. The first proper campsite I stayed at in Luxembourg was excellent value and its location was fabulous. I ended up staying there several days. The walking was amazing.
From Luxembourg I checked out the weather. I decided to head straight to the mountains in Switzerland as it was forecast to be sunny for a week and then rain and thunderstorms Again I stayed longer than I originally planned exploring various mountain walks. I moved on only when the weather broke. Again I had a marvellous time.
But I digress.
I have booked a campsite 11 days before I intend to visit it.
I need to visit this campsite for my research. The last time I planned to go I waited as usual before actually booking a pitch. When I eventually tried to reserve one I was astounded to find the campsite was full and in February. I am worried this may happen again so I thought it best to book to ensure that this time I can go.
So off I go in a couple of weeks. Hope the weather app is correct and there are at least a couple of fine days. We shall see.