As measured by https://www.gov.uk/government/statistics/electricity-section-5-energy-trends, table 5.2. Closes when they publish the results (please ping me if it's up and I haven't noticed yet). N/A if I'm unable to get a number from this source, and I think no number is forthcoming.

I'll choose from one of my own answers.

2020 shows 90,287 GWh and so for 2020 I'd pick 89-91 TWh

2021 shows 88,009 GWh, and so for 2021 I'd pick 87-89 TWh

Update: Q3 2022 has been posted, at 72,866. This is a decline from 75,689 in Q3 2021.

The Q4 report is expected to come out on 30 March.