how do i adjust the door lock on my 1995 sterling europa caravan?

If it's the standard type door lock NO! remove the lock and lay sheet of plain paper over the back of the lock [door side] to mark out the shape and screw holes.
Cut this template out and lay it on piece of cardboard from cerial box or soap powder box anything similar, then cut this shape out marking the screw holes on the cardboard. You'll now have a cardboard shim. refit the lock placing the shim door side of the lock. Try it you may find you need another. In case you fit the lock back the wrong way leave a large window open to allow you to get back in. You could mark the position before reomoving both inner and outer sections

BB
February 2010