Lots to learn in this Caravanning Lark. Just keep asking questions. It may be helpful to know that there is a difference between Damp and Condensation- in Caravanning terms at least.
Damp is generally taken to mean water ingress coming in from the outside, through a damaged seal, damaged window or a crack in the panel. Water gets in from outside and then causes damage in the wooden structural parts of the van.
Condensation is usually from the inside of the van caused by showers, cooking, and breathing. Good ventilation generally manages this as well as wiping down the shower, not drying clothes indoors etc.
Hope this helps
mel