Gas Safety checks
A gas safety check is a good idea when your van has been sitting idle for any long length of time. Hoses can deteriorate, bugs, mud wasps etc. can infiltrate regulator vents and if gas bottles have been disconnected without sealing the pigtail ends any number of insects can make them home.
Generally most hard piped fittings should still be secure, but a pressure test on the whole system soon brings peace of mind.
Of course when a van is sold it automatically requires certification, which covers all of the aspects above.