Robert Silverberg 
Mammoth Books presents When We Went to See the End of the World [EPUB ebook] 

A parody of the end-of-the-world theme in which time travel allows Nick, Jane and their friends to witness the final apocalypse. As a group of friends gather for Mike and Ruby’s party, each couple boasts about their recent trip to the end of the world: a new holiday service available from travel agents at tremendous expense. But as the time-tourists compare their experiences, they soon realise they have not all witnessed the same end of the world.