Thought I’d share my experience as it may useful to others, it isn’t not an advert for OVO!
We are in Aberdeenshire and our Smart Meter doesn’t connect to the Northern Network.
I thought we’d have to accept paying the standard electricity rate for our Vaillant Aerotherm+ but I switched to OVO and added the Heat Pump Plus extra add-on to our tariff. This provides power to the heat pump at 15p / unit, any time. The usage data is taken from the Vaillant database via the internet gateway. Seems to be pulling the correct data so far.
Seems to be a good option for rural areas with no smart meter coverage. I see OVO Heat Pump Plus is an tarriff option on Heat Pump Monitor so perhaps others are using it as well.
They also have an add on for EV charging at 7p/unit which also seems to be working well as well.