I hear what you all say, but I did not say get a smart electric and gas meter. I was running Hive a long time before I haad a smart meter. All Hive, nest etc do is act like a portable thermostat that you can control from either the unit itself or from an ap on your phone. You take your bearings from the room that you are in. If you want to turn the thermostat up or down a bit you sit in your armchair!
Smart meters pose a different problem. The smart part of the gas or electric meter talks to another nuit that lets you see your usage. There seem to be many issues with this connectivity. My Octopus meter took a week or so before it came online and even now I sometimes lose connection. All I do is power the display off, count to 20 then power it back on again and that normally sorts it. I can imagine having a non functioning smart meter is very frustrating but mine works perfectly and I would not be without it.
The Hive/Nest simply hard wires in to your boiler replacing the exisiting wireless thermostat. How many people still use quill pens!