the of things to go over will be the safety side of things how you check ventilation requirements, gas rate an appliance,maybe a soundness check, its not usually an experience test , as its your first visit they cannot check on any appliances you may of notified after installation, they can be useful as well, you can put over any concerns and anxieties you have.
Corgi give good support , and as you start doing the work you should never be affraid of looking for their number on your Corgi card and give them a call they appreciate it and you get the job right,
Its corgi not the Gestapo Good luck in the Job!