https://aclerkofoxford.blogspot.com/2018/12/if-in-day-of-doom-one-deathless-stands.html...Readers of this blog may be interested in watching this series of talks given recently in Oxford (in connection with the Bodleian Library's exhibition Tolkien: Maker of Middle-Earth) on the subject of the medieval languages which interested and influenced Tolkien.
There were lectures on Old and Middle English, Medieval Welsh, Gothic and Old Norse. If you're interested in Tolkien, the whole archive is worth exploring - the Bodleian have made available talks dating back to 2008, on a range of topics relating to Tolkien and his works.
EDIT
The lady giving the gothic talk, Dr Elizabeth Solopova, has a book on the same theme: The Keys of Middle-earth: Discovering Medieval Literature Through the Fiction of J. R. R. Tolkien (ISBN: 9781137454690)