HeinOnline is a database you will find yourself using mainly to source information about American and international law. It does contain the English Law Reports - however, these are also available via Westlaw, which should be your first stop when looking for case law.
HeinOnline has a very large Law Journal Library, which contains thousands of journals on American and international law. The vast majority of law journals on Westlaw and Lexis are UK-focused, so if you are researching non-UK law HeinOnline is the best place to start.
Extensive law database covering law reports, journal articles. Particularly good source for international law journals.
HeinOnline has its own YouTube channel, with an extensive collection of training and support videos.