thats very cheap and not that old either
the usual checks ;
strip and grease the wheel bearings or replace them if they have any rust inside them
check any gas hoses for leaks or replace with new
check for rust in the steel drawbar all the way back to where its welded to the caravan chassis
drain and flush water tanks , do a visual check for mould spots inside them
check the locking clips so the poptop cant pop open and rip the canvas while driving.
put a voltmeter on the lighting / power cables and check for short circuits anywhere
add a modern RCD or ELCB to the 240 volt circuit to prevent electrocution in wet conditions
if it has an inverter , check there is a modern circuit breaker on the batteries to prevent fire in case of a short circuit
give it a treatment to get rid of cockroaches , fleas , tics or bedbugs
/
ummm . i think thats it
oh yeah another one , get out and have a ball