The meat of these words is, really:Jenn had navigated the London Underground, successfully, she supposed, despite getting off at the wrong stop and having to re-board, as she now sat inside a bus shelter just across the road from a grey-bricked building she knew housed Herold’s Talent Agency.
The bit about faffing about on the Tube is added colour and, I suppose, showing the reader that Jenn is distracted by something**. Is this "something" already known to the reader? Or will it be revealed? I hope it's one of these, because otherwise, I'm not sure the Tube-faffing is adding much to the story.Jenn sat inside a bus shelter just across the road from a grey-bricked building she knew to be Herold's Talent Agency.
** - Given that most inner-city Tube stations are below ground***, and so anyone alighting from a train cannot see that they've got off at the wrong station (and thus they have to deduce this by noticing the station name isn't what they'd expected), Jenn must have known the station she required before she got on the train. I can't think of anything, other than being distracted (by her thoughts or by someone/something she saw), that would cause her to get off too early.
*** - Though some on the cut-and-cover lines may, I believe, be open to the sky.