Does this ‘Talk Talk’ network match the information listed here?

https://support.sonos.com/en-us/article/sonos-system-requirements

There’s no reason I can see that it shouldn’t connect to it 

I did a little poking and saw a few complaints by others attempting to connect SONOS to the TalkTalk router. There was some indication that splitting the 2.4 and 5GHz networks was helpful.  Wiring the ONE to the router during setup might help. Make sure that the correct WiFi credentials are entered while the unit is wired.