i did elizabethen but i think i did a different course because we never covered Edward or Mary. i don't think you'd be credited for referencing MQS, because she didn't threaten mary or edward. succession wasn't really a religious problem. i'm not sure how many marks this is, or what the structure would be, but the obvious main theme seems to be religious turmoil. henry introduced protestantism to a catholic country, edward took over, and then mary reverted it. elizabeth did a lot to fix this religious issue with her Middle Way. the fact that it asks "to what extent" suggests you need to consider her shortcomings, and you could talk about a lack of support for her policies: catholic and puritan threat.