The BBC (British Broadcasting Corporation) have a range of great materials delivered over a variety of different mediums. Check out some of these sources:
BBC Bitesize - Bitesize breaks down subjects into easier and more manageable chunks for you to get your teeth into. There are a range of subject areas and activities you can use.
BBC iPlayer - with iPlayer, you can access lots of different tv programmes, from documentaries to news items, all which could help you explore your subject or area of interest.
BBC Radio 4 - Radio 4 has a lot of podcasts, documentaries, as well as news and dramatisations of plays.
BBC Science and Nature - there are lots of programmes (tv and radio) available here for those interested in the Sciences and Nature.