Sorry Peter, sudden deaths are always so hard to deal with. I can say that hand on heart having just lost our Snowy just over a week ago.
PM's are a case of asking your vet asap after they died, so it may be to late depending on when she died. Unfortunately ferrets mask their illnesses very well so often by the time you see any evidence it may be too late, but for someone who does not know that ferrets specific manorisms, it is impossible to spot.
As far as disposing of the body, again your vet will do that for a small fee, but we prefer to have ours buried in our back garden, where each grave has some Crocus bulbs planted on the top as a little reminder each spring.
Sweet Dreams Peccadillo.
sent from my phone, sorry for any typo's.