There was a discussion about the communication channels with Smart Meters here Octopus energy : Smart Meter Feed - #29 by clive
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Re-reading all this, the bit I think I had missed was that you can buy your own CAD/IHD (from Glow for instance) and connect it to your PAN (so you will have more than one CAD connected) as an alternative means to access the meter/tariff data.
The bit that I still see as missing, is the ability to connect something like this stick to a RaspberryPi and then being able to locally use the instantaneous consumption data in your own way. @JaneatGlow care to comment?