"The Trip" is less a film than it is a best-of version of the BBC series of the same name starring Steve Coogan and Rob Brydon. The series consisted of six, 30-minute episodes detailing Coogan and Brydon (playing themselves) going on a trip of Northern England checking out various restaurants for a magazine article Coogan is ostensibly writing. Apparently a good deal of the series actually involved discussion of the food, so the film version dispenses with most of that and just focuses on the interplay between Coogan and Brydon themselves, plus the undercurrent of depression that Coogan's character is going through.
Sounds a bit drab, yeah, but "The Trip" is terrifically funny. Coogan and Brydon (mostly Coogan) spend most of the film trying to subtly one-up each other with impressions and comedy routines. Ah, the impressions, my god, the impressions. You may have seen the dueling Michael Caines bit already since it went a bit viral, but Coogan's Stephen Hawking impression is from just the show and not the film. All are fantastic.