I worked on the gas metering back office team at EON many many moons ago, the general consensus was that if the customer could show that the original meter installers had not thought it through and put the meter in a non-ideal position, then they would carry out the works for free.
If the customer wanted the meter moving so that a new kitchen could be fitted, or other change that the original installers could not foresee then the customer had to pay for it.
There were exceptional circumstances like when a meter needed to be moved to allow wheelchair access or a stairlift etc, but that is down to their discretion.
They did allow local gas men to carry out the work but had to approve it and be given proof of the engineers relevant quals, i.e. MET1.
My advice is to talk to your supplier who will either put you in touch with Transco or will liase with them on your behalf, if you don't go through them, the next time a meter reader comes he will be obliged to inform them of the meter changes and you and your gas engineer will be in bother.
When you do call your supplier, don't be content with speaking to the general customer adviser who answers the phone, insist that you talk to a member of the gas metering team as they will have the relevant knowledge and be able to answer your questions without 'putting you on hold' every 2 minutes while they ask someone else.
Good luck.