I have been further looking at my consumer unit installation (had
problems previously) and noticed my "cooker" feed has 6mm T+E cable
but no electric cooker. Furthermore i have no intention of ever
buying an electric cooker. Instead it is being used as a feed for the
boiler, washing machine, fridge, and microwave. It has now
effectively become a radial socket circuit.

Because the initial wire is 6mm for about 4-5 metres which has a
socket attached, then a spur to a further double socket, am i correct
in thinking a 40amp MCB is too high for this purpose? Would a 32amp
or 16amp be more appropriate or is this not the case due to the cable
being 6mm and requiring a 40a mcb regardless of use.

Thanks in advance.