Can anybody please help me with this Contract Law essay?

This is known as an "issue spotting" exercise. They are not looking for an answer. They are looking for an analysis. The whole business of the slate calls to mind "materiality" and "purpose" as well as damages for breach. The business of the church warden makes one consider who breached first, and whether one party made performance impossible. There is no answer. Instead, inquire into what rules of law apply.