During your grandfather's time in Aden things were relatively quiet. The so-called Aden Emergency didn't start until 1962, and the Radfan Campaign in which British troops were heavily involved, didn't start until the Autumn of 1963. The Northamptonshire Regiment left Aden in February 1960.
So your grandfather would have had a pretty boring time consisting of barrack routines, minor field training exercises and a lot of time spent on the beach or in bars. Better than many people's experience of National Service.