How to add a modal which then opens a ctools modal?
Any pointers as to where I can find a workable solution to this?


If you know jQuery and CSS you can create your own custom modal. Modal one has div id of modal-1 and for two modal-2. 

use the z-index css property, and make sure modal 2 is higher than 1, so it displays on top:

#modal-2 { z-index: 10; }
#modal-1 { z-index: 5; }


Use CSS to center the div, so it appears in the middle of the page, like this. Probably better to use fixed position rather than absolute, up to you. 

Then with jQuery use the .click() function

(function ($) {

  Drupal.behaviors.exampleModule = {
    attach: function (context, settings) 

      $( "#some-show-button" ).click(function() {
        $('#modal-1').fadeIn();
      });

      $( "#some-x-button", "#some-submit-button").click(function() {
        $('#modal-1').fadeOut();
      });

      $("#some-other-show-button").click(function() {
        $('#modal-2').fadeIn();
      });

      $( "#some-other-x-button", "#some-other-submit-button").click(function() {
        $('#modal-2').fadeOut();
      });

    }
  };
}(jQuery));