Post-care is a few day's worth of entry-level painkillers unless the patient gets a dry socket. We use acetaminophen for post-treatment rather than paracetamol, since it's better (never understood the British obsession with that stuff, it's nasty business).
Anywhere else I would walk away from a terrible joke like that, but this is HN. I'm joking.
It's also a rare joke where explaining it won't reduce the effect: by the time a Brit hits the end of the offending sentence, it's too late.
It varies by hospital trust, there is no uniform guideline.
My local NHS hospital sedates for colonoscopy as a matter of course (using fentanyl). But as you say, some don’t, and others ask the patient.
Which is what "gas and air" is in the context of my comment.
I've had like a dozen of colonoscopies (have to be checked every year cause of risk factors), and they were never really painful.
Nitrous oxide is a fairly strong anagelsic (pain medication) but a very weak sedative. That's exactly why it's often used for minor routine procedures where keeping the patient awake and reasonably alert is more valuable than keeping the patient fully sedated.