https://tfl.gov.uk/corporate/about-tfl/what-we-do/docklands-...
It serves the financial districts of London. If you're visiting London, it's worth a look; it's always hilarious to watch people in high-powered suits subtly jockeying for the coveted front-right seat, where the driver would normally sit...
The DLR is automated but there is still a human aboard who makes the decision to close the doors and start the train moving. They can also take manual control of the train if needed.
If that is counted as automatic the Victoria, Central, Jubilee and Northern lines are also automated. They have modern ATO systems as well, it's just the train operator gets their own compartment for historical reasons.
The "sub-surface" lines (Metropolitan, District, H&C and Circle) will have similar levels of automation once their long delayed signalling upgrade is complete.
The more interesting thing is the New Tube for London programme to replace trains and signalling for the Picadilly, Central and Bakerloo lines that plans for ATO without anyone aboard the train (at least where possible, various bits where the lines are shared with other services will need human supervision). But that's currently about a decade into the future, they're mostly still at the planning stage, a report about it is at http://content.tfl.gov.uk/ntfl-feasibility-report.pdf (PDF).