This might be helpful for some, as I have seen alot of people are
asking for a working sample or tutorial.

So here is the easiest and simplest way to export data to Excel from
CakePHP, especially if you can’t install any modules or libraries to
PHP on your host.

check it out
http://www.dnamique.com/cakephp-export-data-to-excel-the-easy-way/