ummmm not sure if i'm getting there or getting more confused .....

so ......
BED A - i can dig up a row of spuds and replace with a row of peas ..... and in spring, i can replace that row with a row of .... something else NOT peas .... (are you counting peas / beans as same type or did you just mean peas only??)

BED B - currently peas, broad beans, french beans - the peas are dieing off, so i can pull them up now and plant cauliflower to overwinter - and in spring, that cauliflower is cut and replaced with ...... something that's not a brassica??? which leaves me with an empty brassica bed next summer???

BED C - currently brassicas - cauliflowers being cut this weekend, could replace them with very late spuds - and in spring i would have to replace with carrots / parsnips etc?

or have i got it all muddled up and should i stick to just one sowing each year??