As someone that works, but doesn't live in London, I found this mildly fun, but can definitely appreciate that it would be near impossible for someone that doesn't visit frequently.
edit: It would also be nice to know some of the technical implementation details - Is the TFL journey planner data exposed via an API?
Having had a (very quick) look at a few of the challenges, this appears to be a Zone 1 and 2 based challenge.
A true Londoner would never stoop so low as to need to refer to a printed map of Zones 1 and 2. Any Londoner worth their salt should be able to give you an immediate un-referenced answer as to how to get between two points in Zones 1 and 2.
Beyond zone two, other than the obvious (POIs, airports, terminal stations etc.) then most Londoners would likely need to refer to a map !
EDIT:
The implementation seems to have a few bugs, for example, proposed "solution":
Stamford Brook - West Brompton - Notting Hill Gate - Bermondsey - Stratford
Appears to be rather curious for more than one reason...
Let's start with the obvious:
"Notting Hill Gate - Bermondsey - Stratford"
Bermondsey[1] is only on the Jubilee Notting Hill Gate[2] is not served by the Jubilee, but Central and Circle/District Stratford[3] is on both Jubilee and Central Line
Therefore try as you might, you are not going to find a train that goes from Notting Hill to Bermondsey and nor is there a direct connection between lines available.
The challenge asks for a "route that passes through all stops". Therefore (I assume) we are only allowing either no connections or direct connections, and not indirect circuitous routes with multiple indirect connections.
After all, most sensible Londoners plan their route that way and would rather, for example, walk, than take a circuitous indirect connection (because walking is often quicker than multiple connections, especially in the central zones).
The other bug:
"Stamford Brook - West Brompton - Notting Hill Gate"
Is just an odd route since Stamford Brook and West Brompton are on different branches, so the answer requires un-necessary tromboning, and in reality there's no sensible answer, because you could equally go "West Brompton - Stamford Brook - Notting Hill Gate", since there's no escaping the Earls Court trombone. Whichever way, it's not a route any sane human would ever take.
[1] https://tfl.gov.uk/tube/stop/940GZZLUBMY/bermondsey-undergro... [2] https://tfl.gov.uk/hub/stop/940GZZLUNHG/notting-hill-gate-un... [3] https://tfl.gov.uk/tube/stop/940GZZLUSTD/stratford-undergrou...
https://www.nytimes.com/2014/11/10/t-magazine/london-taxi-te...
That means you can write bots as long as the bots stay mostly on cached stuff. You can tell if something was cached, because you get a response in tens of milliseconds rather than hundreds of milliseconds.
I've been polling some of their pages every second for many years now without issues since learning that.
There may be some more official way...
Sure is, complete with swagger UI. https://api.tfl.gov.uk/