|"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.
Comic Relief is a British charitable organisation devoted to helping the needy, mainly through fundraising via a biennial telethon. Sometime before his death in 1997, Albus Dumbledore made arrangements via this organisation to have versions of Fantastic Beasts and Where to Find Them and Quidditch Through the Ages published for Muggle readers, with the intention that proceeds from the sales of these books would go towards a fund set up in Harry Potter's name by this organisation and J.K. Rowling.
They are not be to confused with Comic Relief USA.