I've spent a few more hours on study techniques today, and I think my final system will be as follows:
Use the specification as a checklist.
Skim over the content.
Read through it again.
5 minute break.
Summarise all points as google sheets flashcards.
Repeat with a different resource (youtube, other notes, etc).
Keep on repeating until my google sheets flashcards are of a sufficient quality.
Import flashcards to Anki and complete any that are due.
When reviewing Anki flashcards, try to actively think what the answer could be.
After the majority of flashcards are good or easy, blurt out a mind map on the topic, attempting to link as many concepts as possible.
Practice topic questions on Physics and Maths Tutor.