Hello Caroline
Please don't worry about about having the piece of 'kit' as you call it down through the mouth, I had the Gastroscopy done with an endoscope in 2015 (I was bricking it before the day), but afterward I don't know why

You will be given instructions about when you can have a last meal and drink with the appointment.
On the day I felt reasonably calm.
It is one of the kinder procedures I thought afterward.
They use a spray on the back of the mouth, whilst I was reclined.
I said it is only just numbing, so they waited about 2 minutes, is it numb now they asked and I said yes. I think the back of the tongue goes numb as well if I remembered correctly.
They put a little air tube near a nostrill and also a mouth piece in (like a Rugby Players Mouth guard), which I could see had a guide, to guide the endoscope in the mouth and round.
I lay on my left side and followed instructions and got comfortable.
There was no gagging whatsoever and Dr Khan who did the procedure and his two Nursing Assistants were absolutely brilliant

I felt it lightly brush the sides in the odd place when down, probably about twice.
They went right through the stomach and into the tube that leaves the stomach.
It is quite an interesting procedure, no gagging and no pain.
One Nurse just rubbed my hair and reassured me and keep still, going down now, we're through the oesophagus and now we are in your stomach having a look round.
They asked me if I wanted to see inside and I raised my thumb for yes and they moved another screen round in front of my face.
The friendly Nurse sounded like an Estate Agent viewing a property
Please don't worry about the procedure Caroline.
Afterward, I thought going to the Dentist for a check-up when they probe the teeth a bit, was much worse.
Take care all, Mark
Added:
I think once I was set up, I just closed my eyes to begin with and relaxed and opened them when they were part the way down and I could see him moving his fingers to control it.