I've been interested in the subject for a few years, but I know next to nothing about the period (I first learned about it in a 100-level euro history course) and have no idea what books and authors might be most accessible.
(I submitted this the other day, but it was around midnight, so I figured I'd re-sub at a better time.)
I recommended three books here: Robin Fleming's Britain after Rome: The Fall and Rise, 400 - 1070, Guy Halsall's Worlds of Arthur and Peter Heather's Empires and Barbarians: Migration, Development and the Birth of Europe. They are all published recently and so will provide you with the most up-to-date scholarship. They are also very readable, especially Halsall's book. Fleming talks mostly about the period 'from below', Halsall provides a survey of the available sources and proposes a very interesting thesis, whilst Heather gives you a broad overview of what's happening in Europe too, particularly on how the Anglo-Saxon migrations mirrored the Frankish takeover of Gaul. Enjoy :)