Reddit reviews The Canterbury Tales

I'd probably start here in order to get an idea of Britain on the macro scale.
While bountyonme mentions Saxons ruling from 410AD to 1066, the term "rule" is rather loose, as they were constantly being attacked and invaded by Nordic peoples, even having one as their king for a period of time.
And before even that, there was the Roman rule of England, which shouldn't be overlooked, as the Romans had a major impact on the entirety of Europe, and with England so far away from Roman Empire's Mediterranean hub, there was a different flavor of Roman imperialism there than in Italy or France, which left its mark on Britain even after the fall of Rome
Finally, when you're looking at British history, if you're curious about the various cultural elements of the Isles, and how the Brits perceived themselves and others, I would suggest reading Beowulf, with Tolkien's essay on it which examines how the tale provides a peek into the cultural mindset of the period. Also, if you want a somewhat amusing read, check out Gerald of Wales' Topography of Ireland, the section on Irish miracles is especially interesting.
Also, returning to bountyonme, definitely definitely definitely read The Canterbury Tales, Chaucer's poetry is equal parts beautiful and humorous. I would suggest reading it in its original Middle English, if you can get a handle on it. Many of the translations remove much of the beauty and humor of the work, leaving a dry, lifeless piece of shit and besmirching the genius's name. I would suggest this edition if you can handle the price or get it through interlibrary loan, it's well-footnoted, provides a primer on how to read/understand Middle English, and uses the most complete edition of the texts.
Welcome to the confusing/frustrating/entertaining/well-worthwhile arena of Medieval history.

It depends on what you want to read in Middle English. My medieval lit class last semester (full disclosure--I'm a classics major, not English) got me reading Chaucer's Middle English pretty easily. It really isn't so bad after the initial learning curve. I recommend getting this edition of Chaucer's Canterbury Tales--there seem to be some cheaper used copies--and just reading it. It's pretty well glossed, and although Chaucer's ME can be deceptively easy (a good number of false friends), it's more accessible than, say, Sir Gawain and the Green Knight. I'm no expert, but if Chaucer is your goal, read Chaucer. If he's not, I can't really help you, unfortunately--hopefully someone more knowledgeable will comment.