Genre
Comedy; Adventure; Fantasy
Comedy
But hopefully you've figured that out for yourself.
When it comes to Monty Python, there's no using the old excuses that British humor is too dry for you. This movie is funny—that's a fact, not an opinion.
It's been consistently voted as one of the funniest movie comedies of all time, but what makes it so funny? Well, it's a parody, meaning it takes something (in this case a fantasy adventure story) and turns it on its head. Adventuring in the medieval world means defeating rogue knights and monsters, not being repelled from castles by nasty words and using modern weapons to kill bunny rabbits. The humor is in its subversion of everything we think we know about knights, quests, and damsels in distress.
Adventure
But in order to be a parody of adventure it first has to be an adventure. While the narrative format may be rather episodic, it's still one continuous journey… well, maybe two somewhat continuous journeys.
The first is Arthur's quest to gather knights to serve his court at Camelot. We're not sure why—maybe he's preparing for a poker tournament? Then we have the main quest where they all go in search of the Holy Grail—which, btw, Galahad eventually finds, according to the 12th Century legend.
Fantasy
The film takes place in 932 AD (which looks surprisingly a lot like the 1350s, closer to when the Arthurian legends were first being told) so we have the classic medieval warfare with swords and armor and castles and all that good stuff.
There are enchanters and evil knights and witches and temptresses and legendary beasts; everything you need in a good medieval fantasy. And all of these things are redesigned for the sake of parody.
Let's just think about the inhabitants of our story: we've got some rude Frenchmen, cowardly knights, some swallow-savvy guards, eight score blondes and brunettes, a Galahad the Chaste who wishes he weren't quite so celibate, killer bunnies, and a troubled young prince who just wants to sing. This may be a fantasy, but it's not your usual trip through the Middle Ages.