Boyce’s writing is characteristic of the English Baroque tradition, combining clean melodic lines with rigorous contrapuntal activity. It is notable for its rhythmic drive and crisp, clean articulation.
Clear finger articulation across all voices is required to maintain the stylistic integrity of the period.
Comparable difficulty and character — good candidates for what to learn next.
'Twas summer time oppressed with heat is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 'Twas summer time oppressed with heat lasts about 3 minutes.
'Twas summer time oppressed with heat is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Piano Sonata No. 16 in C major by Wolfgang Amadeus Mozart, Keyboard Sonata in D minor by Domenico Scarlatti, Bugatti Step by Jaroslav Ježek — see the full similar-pieces list on this page.