Shakey

well replacing accessories etc on a like for like basis is non-notifiable

replacing a cable - providing same size cable and follows same route - and not in a kitchen or special location (bathroom) is non-notifiable

a spur of a ring/radial not in kitchen or bathroom is non-notifiable

if you were to do a switched fuse spur to sockets in a conservatory, taken off a dining room socket wouyld be non-notifiable, but off a kitchen socket WOULD be notifiable

you see, there are lots of different circumstances, you need to read the approved document to part P, and one of electrical installers guide to the building regs books