so to say,
if i'm going to The Royal Observatory from Waterloo,
i'll have to take the Jubilee Line till Canary Wharf
then transfer to DLR and carry on towards Cutty Sark where i'll alight?

It'd be easier to walk over the bridge to Waterloo East and if there's
a train to Maze Hill from there, get on it, otherwise change at London
Bridge.