Bach's Well-Tempered Clavier is a cornerstone of keyboard repertoire, exploring all major and minor keys with profound contrapuntal mastery and emotional depth.
Developing complete independence of the hands and achieving clarity in complex contrapuntal textures are paramount.
8 Fugues from J. S. Bach's Well-Tempered Clavichord is rated Henle level 7 of 9 — late advanced repertoire, roughly ABRSM grade 8 and above. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 7 — meaning you can already play level 6–7 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
8 Fugues from J. S. Bach's Well-Tempered Clavichord is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.