The bowel prep I had was taken before going to bed as well as the morning of the day before. so I was thinking more along the lines of waking up with that urgency and subsequent hours of toilet torture that follow.

True enough you could skip sachet B though and save yourself the afternoon.

I don’t know what other preps are on offer (or even what the one I had is called) I’ve been fortunate enough to only have to have the one colonoscopy, so I can only draw from that one experience; I’m definitely not a prep expert or anything like that.