Better check with your local Inspector on that issue but as far as we go here we use copper pipe for everything so I cannot personally see any problem with what you are intending to do.
I would however offer one serious piece of advice – hire the services of a suitably qualified gasfitter who will ensure your installation both meets all the legal and safety requirements which will give you peace of mind.
It is always safer to utilise the experitse of a qualified person when playing with gas appliances and pipework because even the smallest of leaks can cause the biggest of explosions and risk to both property and life.
Selgas Services Ltd
Craftsman Gasfitters, Plumbers, Electrical Service Technicians