James Campbell's (ed.) Anglo-Saxon England is a fairly popular and widely-read way into the period. Frank Stenton's 1943 magnum opus is still regarded as something of a classic, though it is a bit outdated and the first few chapters aren't really worth reading except for historiographical purposes. That said, it's a massive book that you can get pretty cheaply. Robin Fleming's Britain After Rome mostly covers the Anglo-Saxons and is a pretty good intro. In terms of documentaries, I'd recommend Michael Wood's stuff, whether from the 1980s or the 2010s. What I'd really encourage though is that you have a quick glance at a primary source. Here's a link to Bede's Historia Ecclesiastica. He was biased in many ways (particularly against the Britons/Welsh), and Book I contains a lot of stuff we know to be incorrect, but his well-researched history is probably the single most important source on Anglo-Saxon history. http://www.gutenberg.org/files/38326/38326-h/38326-h.html