Although it is not illegal for you to carry out the work, the law states you must be competent to do so.
Being competent implies that you must use the associated equipment ie. a manometer, and you must carry out correct test procedures to ensure the safe installation of the appliance, ie. pressure drop test and gas soundness test.
Your appliance, though new, may for instance have been damaged in transit and what seems like a relatively simple procedure of connecting a bayonet may have wider implications should a leak occur.
All freestanding gas cookers must be secured to prevent them from falling over either by means of a stability bracket or a chain fixing to the rear wall.
Another point to consider is the question of insurance should damage occur as a result of incorrect installation. An insurance company would only be likely to honour their policy once satisfied that the installation was carried out correctly.
I don't mean to scare you away from a task you feel fully capable of and you may well have the equipment and know how to complete the job successfully, but not many consumers are aware of the wider, unseen responsibilities that are consistent with installation of gas appliances.
I hope this helps you and if you require further advice I will be only too happy to assist,
Regards,
Tim. ;D
T Foley Installations Quality kitchen design and installation
www.kitchensfitted.co.uk