Despite all that meter and the end rhyme, "Aubade" doesn't really sound too, well, poet-y. It sounds more conversational, like the way some fairly-educated, grumpy guy would talk. The word choice and the descriptions are all pretty down to earth. If you don't believe Shmoop, just check out line 1: "I work all day, and get half-drunk at night." It doesn't get much more real-world than that (and we don't mean the MTV show; we mean the actual real world).
Sound-wise, Larkin also mixes in some interesting consonance in this poem. Line 5 is a good example:
Unresting death, a whole day nearer now.
Hear those repeated Ds and Ns? That's it. It ties the line together nicely, making each word seem like it fits, belongs exactly where it is. In this line, the consonance also subtly reinforces the connection between "death" and "day." Remember, in this poem daylight doesn't push death away. Death is still there when the sun comes up. It's not as simple as sunlight and vampires in Larkin's world.
Larkin lays some more consonance on us in line 10:
Flashes afresh to hold and horrify.
This time it's the Fs and Hs that steal the show. In this line, the repeated sounds kind of mimic the flashing action the line describes. Just like the meter and rhyme scheme of the poem, the use of sound here ties the delivery together in a subtle way, helping the main idea along. Neat, huh?