The Party Superstore was/is my absolute favourite London shop until it was bizarrely attacked and gutted during the summer London riots. They have been since adopted as a concession by the local Debenhams but you can still savour the full delights of the products and nonsense on line.
There's something about this street, probably the fact that it's pedestrianised, that makes it feel like holidays. It also has a solid range of bars (Cafe Kick), restaurants (Berber & Q) and cafes (Brill) so is a good option for all times of the day. They have a quality variety of street food vendors operatin during the day, and fairy lights help it to come alive at night