Can I fit a 16 amp fuse into a UK domestic 13 amp plug?
Whether or not it can be done, I cannot recommend it. By putting a 16A fuse in a UK domestic plug you are potentially overloading the cable (max for a UK domestic plug is 15A rated according to this pat testing website).

A spur off a ring main, using 2.0mm2 twin and earth cable is rated for 20A. Two 16A plugs into the sockets on that spur could hence significantly overload it, starting a fire in your walls.