I am officially connected! Speeds are fantastic and the engineers were in and out in just over an hour - they waited to make sure the connection got provisioned. As expected though, the wifi signal drops pretty badly when I move to some rooms of this old flat.
...and I still haven't heard a single thing from TalkTalk since I ordered
Yeah the engineer said they don't carry Eero routers. Someone from TalkTalk tried to tell me yesterday that CityFibre is incompatible with more than one Eero. The engineer confirmed that is a load of nonsense. I'm going to push TalkTalk for another router given the barefaced lies some of the agents gave me, but I don't expect to get far. Worst case, I'll buy another Eero around Black Friday.