It may buy him some time..or it may not depending on the severity of bearing failure.
I would also not waste the time to replace a pinion seal for a leak if the diff is in fact making noise.
If the OP has some sort of obvious binding in his LR3 driveline, there is something wrong that needs to be addressed.
Things I would look for that could cause binding in the driveline

1)Emergency Brake Shoes delaminated and jammed up in the rear brake rotor

2)Brake caliper hanging up, seized caliper piston or sliding pins

3)Wheel bearing catastrophic failure front or rear causing brake rotor to rub on brake components and bind or seize

4)Front or rear differential pinion or carrier bearing failure (catastrophic) causing the pinion or ring gear to be loose, wear excessively and possibly bind/jam up.

Cheers