On a budget, skip Warner Bros. Studio Tour London – The Making of Harry Potter — the spend outweighs the payoff.
£53.50+ (coach extra)
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.