Warner Bros. Studio Tour London – The Making of Harry Potter is a real time commitment — fit it in only if it's a priority.
Allow 3.5–4 hrs + travel.
The actual sets, costumes and props — Diagon Alley, the Great Hall, Hogwarts Express, Butterbeer — and it delivers hard for fans. The catch: it's near Watford (a paid coach or train ride out), tickets must be pre-booked weeks ahead, and it's not cheap for a family.