The University of Reading have put together a number of handy study guides for its undergraduates. Although some of the guides are focused on writing dissertations or working on large data projects, the more general advice on structuring and writing essays will still be really helpful for A-Level students. And who knows, you might want to look at some of the other guides to get a sense for university undergraduate-level work!
University of Reading Study Guides
Resource type: website
Subject Area: Anthropology, Archaeology, Architecture, Biology, Chemistry, Classics, Computer Science, Earth Science, Economics, Engineering, English, Geography, History, History of Art, Languages, Law, Linguistics, Mathematics, Medicine, Music, Philosophy, Physics, Politics, Psychology, Religious Studies, Sociology, Veterinary Medicine