|"Is this all real? Or has this been happening inside my head?"
The topic of this article is of a real-life subject that has been mentioned "in-universe" in a canon source. The Harry Potter Wiki is written from the perspective that all information presented in canon is true (e.g., Hogwarts really exists), and, as such, details contained in this article may differ from real world facts.
Pudding Lane is a street in London, England. Although mostly occupied by Muggles, there was, possibly, at least one wizard living in it during the 1660s. The Great Fire of London in 1666 started on this street, though there is debate whether it began in a bakery or in the basement of the house next door, where legend has it a young Welsh Green was kept.