Yes, Home Assistant is the electronic equivalent of a garden shed or allotment, although it does not actually get you out of the house.
Glad to hear that you managed to get it all working. This discussion is really about graphing Octopus Energy integration, but you may like to post your Node-RED flow, sensor, and card configuration for others to learn from. I would suggest posting a new discussion, tagged as Node-RED as NR is quite a niche area for HA users.