Pulling Advanced Custom Fields from other pages

Question

Basically I am using Advanced Custom Fields and have an ajax tabbing system that works with the ACF.

The current set up is below:

<ul class="css-tabs">
      <li><a class="current" href="/wp-content/themes/blue-and-grey/uni-general.php">General</a></li>
      <li><a href="/wp-content/themes/blue-and-grey/uni-courses.htm">Courses</a></li>
      <li><a href="/wp-content/themes/blue-and-grey/uni-inthearea.htm">In the area</a></li>
      <li><a href="/wp-content/themes/blue-and-grey/uni-sportsandfacilities.htm">Sports & facilities</a></li>
    </ul>

At the moment, I am loading external php documents through AJAX, only problem is, the php is not loading as when echo'ing that field, it cannot be found as it is held elsewhere.

How can I use the custom fields to display what's in that page template, that is held elsewhere?

I current am using:

<?php echo the_field('current_students'); ?>

To display the field, but where it's an external PHP document, it doesn't work.