The Profile app, released in v11.2.3 will show you the average usage per hour for each month, which will give you a good idea, but won’t be exactly what you’re asking for. I can’t think of anything better without writing a script.
Also note that Octopus are looking at the previous 10 working days, which makes it trickier.
Thanks Timbones, did not know this and then found this on their FAQ:
We’ll look at your historical smart meter data leading up to a Session, and calculate what you usually use at that time of day, on average.
If the Session is on a weekday, we’ll look at your half-hourly usage over the last 10 weekdays (excluding saving session days). If the Session is on a weekend, we’ll look at your half hourly usage over the last 4 weekend days. These half hourly averages are then subject to an ‘In Day Adjustment’ which will make adjustments based on how much energy you’ve used on the day of the session.
We then use these adjusted half-hourly averages as a benchmark – so you’ll earn points for every kilowatt hour you save compared to that number during your Session.