Because the smart meters in my house are in no way smart whatsoever, I have continued to do what I've always done and taken regular meter readings myself.
In the last 21 days my use amounts to:
£103.50 in electric
£54 in gas
Some basic maths suggests my monthly use will work out at
£152.65 for electric
£79.70 for gas
The £66 per month discount for the next six months is a nice little bonus, but in reality it's likely to get gobbled up by increased central heating use.
The continual rise in pricing however means that the Tree family has agreed to fit solar panels to the main roof, the extension (when it gets built) and the annexe going in the garden next summer. The new underfloor heating will all be electric, we'll include a couple of big batteries for storage and install a reversible air-source heat pump so we can have solar-powered A/C in the summer and a little extra backup heating in the winter.
I looked into how to disconnect from mains electricity and there is a hefty fee involved - what a surprise.
EDIT: Mrs Tree has proposed an experiment for next month: no charging of mobile phones in the house. We're going to charge them at work, or in the car. Might not save much, but it's an easy change to adopt so worth trying.