Given that Bernard Bresslaw did play the Ice Warrior Varga in Doctor Who, I reckon playing Detritus would be easy by comparison. Pity he's dead.
As for Bernard Cribbens, you have got to be kidding me. I've seen him acting when he was younger, and while he may just have the earnestness for the role of Carrot, he's not big and tall. He's a good actor and all, but...
Yep, that's given me nightmare fuel. And now, I welcome the sweet, sweet embrace of death*...
*Not really.