Is it safe to screw into the internal wall?

GarethDavies

I've been caravanning for decades, and on my fifth (I think) caravan. But I've never in all that time dared to fix anything permanently on to the internal walls, for fear of creating expensive damage. Now I find I need to fix a little corner shelf, one side
of which will need to be attached to the internal wall. Is this advisable, and, if so, what kind of screws etc. would I need?