After being stuck underground for fifteen days, the narrator comes out to find things radically different. The countryside that he thought he knew is now the "weird and lurid" landscape "of another planet" (2.6.1).
The narrator feels that he understands what a rabbit might feel when confronted with some human interference in his rabbity life. He feels a sudden "a sense of dethronement, a persuasion that I was no longer a master, but an animal among the animals" (2.6.2).
That feeling doesn't last too long because he's so darn hungry. He finds a nearby garden and eats some veggies he finds – which is totally what a rabbit would do, if you think about it.
He starts to move west (away from London), but there's a flood that stops him. See, the red weed has choked up the rivers, causing them to overflow. The narrator ends up heading east, toward London.
Don't fret about the red weed, thought. The narrator notes that the red weed died off pretty quickly because of infection that all earth-plants can fend off.
As he walks toward London, he notes that the "scenery changed from the strange and unfamiliar to the wreckage of the familiar" (2.6.8), which we guess is an improvement. We're not sure.
The narrator finds no people and only scraps of food. He imagines that he's the last man on Earth and pictures the Martians off elsewhere. Maybe they're summering in Paris or enjoying the nightlife in Berlin.