I assume by gas meters you mean domestic meters for fuel gas/methane? In which case the Dangerous Substances and Explosive Atmospheres Regulations will cover this. I doubt if DSEAR will explicitly refer to gas meters, rather than the general principle of ensuring dangerous substances are managed accordingly/safely. I would expect gas meters to be purged with a non hazardous/flammable gas, prior to transport and a 'gas free certificate/declaration made'. Although I can' image there is that much gas in a meter, being transported. Maybe transportation in a well ventilated vehicle is sufficient? As ever, risk assessment is the key, which the DSEAR require you to do.

Would you recommend doing that to keep any residual gas in the meter or would you suggest not doing it to make sure that the gas vents from the meter?