u/Dazed_And_MoreBooze

I am planning on driving into mainland Europe and going through some countries (France / Belgium / Luxembourg / Switzerland / Andorra / Spain) from late July to mid August.

I was just wondering how necessary it is to book campsites. I have found many campsites, and for most campsites I wouldn’t be staying for more than 1 night. Would it be necessary to pre book / prepay or would arriving on the day be ok?