Suggestions:
Read every book you can get your hands on. Remember than much of the canon is available free on Gutenberg.
Don't be limited by the A level syllabus.
Read as many C18 to C20 novels as you can, as much C16 to C20 poetry as you can, and as much Shakespeare as you can.
Have a look at this -
https://www.prospectmagazine.co.uk/culture/60328/lips-and-ledges-the-writings-of-john-careyMaybe read some John Carey, Ros Ballaster, and Terry Eagleton.
You could perhaps check out Seamus Heaney's translation of
Beowulf, and look up JRR Tolkien's essay
Beowulf and the Critics (people sometimes forget that Tolkien's main job was being the Merton Professor of English at Oxford, not writing nonsense about hobbits).
You should be able to read Chaucer in the original, with a crib, but poems like
Piers Plowman and
Gawain And The Green Knight are trickier.
Tolkien's translation of
Gawain is quite good. He never completed his translation of
Beowulf (too busy writing nonsense about hobbits). There's a good recent film of
Gawain, which captures the magical strangeness of the poem.
Here's
The Wanderer in Anglo Saxon and in modern English -
https://www.tloneditions.com/Ezequiel_Vinao_The_Wanderer_translation.html