Where is the fuse in a plug?

there's no fuse in a plug that I know of......you might be thinking of GFCI

Answer

All UK plugs are fused. The fuse size is chosen based on the equipment that the plug supplies, up to a maximum of 13 A. This is because British 'power circuits' are ring-mains, not 'radial circuits' as they use in North America, so any equipment plugged into the ring main must be individually fused at their plug. The fuse is accessible by removing the plug, and rotating it so the pins face you. The fuse is located behind a small, rectangular, plate that must be removed to access the fuse. On older plugs, the plug must be dismantled in order to access and change the fuse -a quick and easy job, as it is held together by a single screw.