How should I structure my answer to 40 mark questions?

This is a complex question but to keep it brief you should follow the structure of having a brief introduction outlining what you will write about in the essay, then use the structure of PANEL for your points of argument or discussion, which is Point, ANalysis, Evidence, Link, and you should aim to make 3 points of argument before concluding and making a firm final judgement on what the question asked.