Open every door,locker wardrobe, bed box and draw.
feel for soft spots and discoloration or a texture that looks different, and most of all use your nose for musty smells. this should include all around the roof and floor where the walls meet, dont forget the roof vents and around the area of fire vent and status ariel, also walk up and down the van, does the floor feel spongy (delamination).
Window rubbers, look in the corners again for damp or discoloration.
Tiny but long hairline cracks in sidewalls of the tyers and cracks in between the treads where most people dont look.
If it does not have a spare wheel dont buy it unless one is thrown in for free
The list could go on, if you have a printer try and print this
you might have to enlarge it a bit to read it but it could help you to check it out
Enjoy your new caravan
Thank you for the helpful advice. We took on board everything you mentioned above, and found no faults with the caravan except one of the tyres had cracked, which they will be replacing both.
All happy and picking it up on the 1st Aug :)