Ellie will take a closer look at the western building first.

It has an official solidity to it, with many high windows and a vaulted entranceway. More of the orange-eyed men and women are coming to and fro from it, along with several well-dressed londoners. 

Hhhhhow about the eastern building!

That one's got a large courtyard swarming with uniformed police!

Swarming like they've got a purpose or swarming like they've nothing better to do?

Mostly like they've got nothing better to do. Some of them are puffing thick black cigars; others are riding penny-farthing bicycles back and forth as if training; still others are hauling apparent suspects to and fro. 

Okay, cool.

Does anyone stop her if she enters the courtyard and tries to cross to the building?

No-one stops her. She is now in the middle of an old-timey police station with an attached bar.

"Oi," says one of the policemen. "State yer business."

"Hello. I'm looking for ways to orient myself in the city, as I've just arrived."

The copper eyeballs her. "Do I look like I've got all day to show around surface tourists? G'wan, get."

"So there are ways to travel between here and the surface?"

"Yes?" The copper's eyebrows rise. "The Canals. Didn't you come down 'em?"

"No, my transition was rather more sudden. Hence my disorientation."

"I see." The copper tucks his thumbs in his belt loops and frowns. "Well, if yer want to go back up the canals start jus' south along the coast." 

"Which way is south?"

The copper points back down the road that Ellie came up. "Usually that way."

"I see. Thank you. If I may trouble you for one more question, is there a library or similar anywhere down here?"

"You can always try the University, I s'pose. It's by the river and up a ways."

-Canals to the south (way out?)
-University maybe has library (upriver)