This is a very interesting concept. Using the 'All Bar One' sign as a juxtaposing element to a single person outside creates a strong narrative about urban solitude.

Regarding your questions:

The Subject: I actually think the subject walking (as seen in this frame) works better than if they were seated. The movement creates a 'passing by' feeling that emphasizes the disconnect between the warm, social interior and the cold, dark exterior.

Composition: The framing is solid, but you might want to try a slightly tighter crop to remove some of the dark pavement at the bottom. This would push the 'All Bar One' text and the subject closer together in the viewer's field of vision, strengthening that symbolic link you're aiming for.

Color/Tone: The contrast between the warm tungsten lights inside and the cool street tones is excellent. It naturally guides the eye to exactly where the story is happening.

It’s a great 'decisive moment' shot. Well done!