coffeeman wrote:

I obviously want to box the meter in securely with a lockable door for
access (I assume this is legally necessary too?).

Well it certainly needs nothing other than the standard triangular
lock/key that the gas-meter readers carry; whether you're allowed to
leave it totally unlocked I don't know. If it's on your land away from
the public footpath where vandals could wreak havoc, I expect it's
probably OK unlocked.

David