I will get this Bongo sorted out eventually!!

I have just got a letter from my insurance firm. It looks like I have to prove that my Bongo is a camper van and doesn't just have a matress thrown into the back. No problem, a few photos will do the job! But, I need my LPG gas system to the gas rings testing so I can send them in a certificate.
Does anyone know where I can have this done or someone who can come to me to test my Bongo? Any help would be appreciated.

Regards, Ken