CMOT must be George Cole in Arthur Daley mode:-)

Lord Vetenari - Alan Rickman`

Nanny Ogg - Pam Ferris (or, giving it a folky flavour, how about Norma Waterson;-) )

Death's voice could be none other than Christopher Lee

Simon Pegg could make a good Rincewind (Or Jasper Carrot in his younger days!)

Cheers

Dave