My rear diff is knackered and I need to remove it to inspect it and also check if the prop shaft and/or rear drive shafts also need replacing. Can I drive it while these are all removed or do the rear hubs need at least the stub end of a driveshaft fitted in them to 'stop the wheel bearings collapsing', as one garage has told me?

The rear hubs needs at least the stub end of a driveshaft fitted in them to 'stop the wheel bearings collapsing', are absolutely correct!
Except for this, remove prop shaft, diff and the rest of the rear driveshafts.

Thanks for confirming that.