This is probably a silly oyster-noobie question, but I'm finding the tfl
online advice clear as mud.

I only use oyster on the buses - so what happens when my funds run out?
Firstly, auto-top up doesn't work with buses, and secondly when I
tries to add funds online, it said I would have to activate the added
funds at a Tube or DLR station. Is this right? Can't you add funds online?

Help much appreciated

CC