I really like this idea. Quite often I am checking train times, etc, especially at work.
I really dislike the idea of relying on something like AWS to make it work, though. If I invest into an IoT/hardware project, I want it to still be usable in 10 years time, not e-waste due to the random whims of Amazon.
In theory you could query the national rail feeds directly: https://www.nationalrail.co.uk/developers/
I may try it sometime with my ESP8266 watch!