To have the hump in the UK means to have the blues, or a spate of depression or irritation. Also to ‘take the hump’ is to take offense.
In the waiting room of Dr. Plankk's office Lionel reads a magazine and observes that Mafeking's been relieved.
You can read about Mafeking, which -- in the short version -- is a town in Africa which was liberated and celebrated around 100 years ago during the Boer War, but it really is not relevant. The point Bob Larbey was making is that the magazines in doctor's offices are very old. If you still insist in knowing about it -- go here: http://www.mcgonagall-online.org.uk/poems/mpgmafeking.htm
After the doctor's visit, Lionel returns home without Alistair, prompting her to ask if they have kept him. Lionel says that it was a surgery, not a hospital.
In the UK surgery refers to a dentist’s or doctor’s office.