Walk along the Thames to enjoy views of Big Ben and the city; the London Eye operates into the evening (check exact hours), good for sunset/early evening rides.
Dine at a Covent Garden restaurant (e.g., Clos Maggiore or The Oystercatcher) then see a West End performance; theatres usually start shows around 7:30pm–8:00pm.
Dine at a Stratford restaurant (e.g., The Opposition Bistro) then attend a Royal Shakespeare Company show if available — evening performances typically start 7:30pm–8:00pm.
Guided or self-guided walking tour past Radcliffe Camera, Christ Church and the Bodleian (the Bodleian tours often start around 10:00am — pre-book if possible).
Visit the iconic college and walk the scenic Christ Church Meadow; college opening times vary — check online for access/fees (often early afternoon entry allowed).