It would take me a couple of hrs to tell you the rules and regulations regarding installing and commisioning a gas cooker. The main rules and regs are as follows :-Building regs Part A, Part B, Part F, Part J and Part L. Along with British Standards BS 4086 , BS 5386 / 1-5, BS 5588 / 1
BS 6172, BS5440 / 2 And BS5258. And in accordance to the manufacturer's instructions.
But i find this question disturbing as you're installer will know all these rules and regs anyway and advise you if any re-medial works need to be carried out to surrounding areas before he would install the appliance and sign it off. Unless & I suspect you are going to attempt to install the appliance yourself ( DIY ) ? This is i am sure you are aware is illegal and further more invalidates home insurance's. Also just like TV liecenceing The Seller will have notified the authorites of the purchase and CORGI will be waiting for the appliance to be notified as installed to full complience to rules and regs. They will only then issue your compliance certificate for you and the home owner sellers pack
PLEASE use a CORGI registered engineer qualified to at least CKR1 ( cooking appliances ).