I wouldn't worry too much about it mate. Can't speak for your inspector but the chap round our way is very good.
They want to make sure you know your way round your tools, what to use where, and that you are covering all your mandatory checks.
Make sure you have all the correct labels and paperwork with you, and also make sure you have your Viper book or whatever training manual you used.
If you don't know that answer to something they ask you, you can always say you will look it up, and do it there and then if needs be.
They answered any questions I had, he understood that I was nervous,and some stuff will slip out of your mind, he just give me a gentle nudge.
Most of them a have been in the trade a long time, and I can imagine could spot a chancer a mile off.