Decision making and consent
Read "The Seven Principles of Decision Making and Consent" (all seven principles with focus on Principle 5), then read the section "Circumstances that affect the decision-making process (part 3 of 4)" specifically paragraphs 76-86 covering mental capacity definition, presuming capacity, and assessing capacity to understand clinical application of the capacity framework. (30 minutes)
General Medical Council - 2015
Click https://www.gmc-uk.org/professional-standards/the-professional-standards/decision-making-and-consent link to open resource.