Why would you wait for her to ask you how long you want when you could just tell her?

The police station thing seems like mere coincidence. I mean, they have cars. They don't need to set up stings in walking distance.

You had said she's well reviewed....any reviews from this month?  If not may be a red flag...
but if she's reviewed from this month she should be speaking truth...

I think you are probably being paranoid.  If she has 40 reviews over three years, she is not LE, and unlikely to be cooperating with them.  

You also said that you were available for an hour...she presumably saw that, and has scheduled accordingly.  

As for a police station being a block away, that probably doesn't mean anything.  She may not know, and you might want to mention that to her.  As for her changing locations, smart providers do that.  I remember a time several months ago when meeting my ATF that there were three marked LE vehicles parked within a block of her hotel...I just walked past them, as I didn't think they would stop little ole me.  They didn't, but she was quite interested when I told her of the gauntlet I had just walked through.  FYI, she no longer uses that hotel for incalls...

With 40 reviews, she is almost certainly safe to see, but may be complacent about her surroundings.   You might want to mention your concerns to her before meeting...

Years ago I frequented a MP that was across the street from the police station.  I never gave it a 2nd thought BTW, this was over 10 years ago.

Based on the fact pattern you described, the chances that the provider is LE is very slim. If she is well reviewed by credible hobbyists, you prob. have nothing to worry about.

But whether you are a first time hobbyist or an experienced hobbyist, if you are not comfortable with the totality of the situation and have any doubt about any aspect of the experience, than I would suggest not going. As they say, trust your gut. Do what makes you comfortable.

The bottom line is there is A LOT to think about in your first session (heck, prob. your first 5-10 sessions until you get the feel for how things work). From how you greet the lady, to how you handle the donation, to how you move things along, to what is and what is not permissible sexually, to how you end the session, to how you say goodbye, etc. All these things are nerve wracking until you figure it out. The LAST thing you want to concern yourself with is the legitimacy of the provider as you are walking into the session. If you have any doubt about whether you are the target of an LE sting, no matter how ridiculous or crazy your beliefs may be, than do not see that provider. See someone else.