I have no display showing on my gas metre could this be because of battery?

I presume this is a smart meter since you mention a battery. Given the device is, as you say, battery powered it is typical for the display to turn off to save power. You’ll have to click one of the buttons to turn the display on. It’ll then timeout and turn off after a few seconds, just like a phone or tablet does.

@Hooloovoo, not all digital gas meters are smart meters. But functionally when trying to read consumption manually they are very similar.