Re: aikido for police
Short answer: yes. Now, some styles might be better for you in this regard, but instructor/dojo may matter more than style. Some schools are more martial than others.
For the record, the style taught to the riot police is Yoshinkai. However, I recall hearing positive testimonials from police officers studying many different styles.
Try a few classes, see if you like it. What it's doing for you 'practically' may be hard to tell at first, but try to gauge that a little as well. I think you'll need to do most of the assessment here, not us.