Yes, very happy for you, now the learning begins.
As an old hand said to me "everyone makes mistakes, you've just got to hope you get back to them before Transco".
If you do wake up in a white sweat wondering whether you put the screw back in the test point of the gas meter, just go back in the morning and say you think you left your favourite tool can you just have a look.
If a customer doubts your judgement, don't back down, you know what is best regarding issues of gas safety, if they won't have it your way walk out. If the situation is dangerous phone Transco and put the decision into their lap as to what to do.
If a member of the public phones you with what might be a dangerous situation like a gas leak, first give advise, second advise they ring the emergency service provider, third get round there fast yourself, and if you can't go call the emergency service provider yourself and put the ball in their court.