Georg Philipp Telemann's 36 Fantasias (TWV 33, often published in sets of 12) are landmark Baroque keyboard works. They showcase a blend of Italian and French styles with accessible yet sophisticated contrapuntal writing.
Focus on clear articulation, steady tempo, and stylistic ornamentation typical of the Baroque period.
12 Fantasias for Keyboard is rated Henle level 3 of 9 — late beginner repertoire, roughly ABRSM grades 4–5. In the RCM system it corresponds to about level 7.
You should be comfortable at Henle level 3 — meaning you can already play level 2–3 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
12 Fantasias for Keyboard is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.