Alwyn Evans (Mark Bonnar) is seen reading John Wyndham's classic sci-fi novel, The Kraken Wakes, in which invading aliens from outer space lurk beneath the seas before emerging to destroy mankind.
Baz is playing Battlefield V towards the beginning of episode 1. Actress Rochenda Sandall (Cat) was a voice talent on that game.
The book that Alwyn is reading in episodes 1 & 2 is The Kraken Wakes by John Wyndham which is about an ancient life form below the sea that feels threatened by man and responds in much the same way as this.