I would imagine up to the gas meter should be the gas suppliers problem.
They changed my gas pipe and gas meter from the road and because the pipes were old and were doing everyone house on the street.
Obviously no charge to the householder but did notice that the pipes were to broad for the meter to fit so they just added a flexi type of pipe to join it up. It took no time at all to do it.
If they want to put a smart meter in without you ordering one they should not charge you.
I am only talking about my experience so do not know your circumstances.