Gas Mains pipe / valve entering the house, can I build a porch around it? Information, help and advice on many gas related subjects from gas fires to domestic appliances

[Zoltan]

I would like to build a porch in front of my front door but the mains gas pipe (with what seems to be a valve?) is in front of my
front door and the porch would enclose it.

Am I allowed to build a porch around it (and enclose it) and if not can I move the pipe/valve further away from the door so it would be just outside the porch door?
Do I need permission from the national grid or someone else to do either (either enclose it with a porch or to move it)

Thank you in advance for all the advice!
Zoltan.