When I was a college Freshman--and a lot more inquisitive--I read portions of his translation of the epic poem "Sir Gawain and the Green Knight." It was VERY, VERY dry, even the annotations. This is stuff that only another academic could love.
Tolkien stood astride two worlds: That of the scholar, and that of the author of fanciful fiction.
The twain really didn't meet at very many points.
It's titled: "Harry Potter Passes The Socerers Stone Into The Chamber Pot Of Secrets".
I'm looking forward to it.
L
Actually, Middle English is the English for approximately the Norman Invasion until the mid-1500's, showing the influence and adoption of French words and grammatical structures. The London dialect of Middle English is what Chaucer wrote in, while the Pearl Poet (Sir Gawain and the Green Knight) wrote in a Northern dialect of Middle English.
Tolkien was a Professor of Anglo-Saxon (that's Old English) at Oxford. Beowulf was written in Old English (probably first written down about the year 1000 AD, before the Norman Conquest, but composed two hundred years before that). This is an important point for me, since I did my grad work in Anglo-Saxon and Old Icelandic Literature.
Soþlice! [truly!]