Why do you think you need these fuses Tony? Your distro already has 16A breakers, and this is perfectly adequate. Appliances with 0.75 mm2 cable are quite satisfactory under short circuit conditions to trip a B16 breaker long before the cable gets too hot. Is this a curious request from H&S, because if so you need to push back because there is not a safety issue here. Try it out one day, a length of 0.75mm cable with the ends shorted. Try switching it on and the breaker will trip quite quickly, no flames or anything else interesting!
The cable rating of 3A (or whatever) is not its fault current rating, this is calculated from the adiabatic equation, which will give you a final conductor temperature. Just don't put a 5kW lamp on the end of a 0.75mm2 cable, because this is the overload condition, not the fault one and the cable will get very hot indeed (although probably not catch fire).
Well I think Dave Z has summed it up nicely, as AJJ and MAPJ too. Do you really need to fuse down? Harry gave a good suggestion if you really do need to.
