Thank you very much for all the replies.
I've done some research and in terms of how much gas it consumes, it says:
4 Gas Burners : F/Left 2kw, F/Right 2.9kW, R/Left 2kW, R/Right 1kW
which = 7.9kw for the hob, plus I don't know how much for the oven / grill.
I've read all your thoughts...