House of Commons Library Briefings
A great resource for all political researchers, and in general people who want to appear more knowledgeable on a subject than they are, is the House of Commons Library. The external HoC Library website is a bit less accessible than what is available for researchers with access to the Parliamentary Intranet, but there’s still a lot of good briefings on pretty much every subject that’s been debated in modern politics. The service also includes briefings from the Parliamentary Office of Science and Technology (POST) which covers more science-based policy issues, including energy generation and climate change.
Research Briefings are longer, more in depth papers; standard notes are more brief summaries of an issue for someone who needs to be brought up to speed fast.