littlebabyjesus
one of Maxwell's demons
Tate Britain. Most people think of Tate Modern when you just say 'Tate' nowadays.The Tate, the one with the Turners.
C10 bus goes all the way from Lower Marsh, which is a short walk from Waterloo. Depending on exactly where you're staying, there may be good bus routes like that that pass near Waterloo. You haven't asked about the IWM. I'm guessing you'll walk there?