How can I get the homepage from the loop?

That depends on what your trying to do.

If you want to get the page content in another template or functions file and your home page is a page that you created in the dashboard and set as the static front page you can use get_page_by_path function like this:

get_page_by_path('the_path_of_the_page'); // Usually will be 'home'

Or if you want to use get_pages you can do the following:

<?php $args = array(
    'post_type' => 'page',
    'post_status' => 'publish',
    'post_name' => 'the_slug_of_the_page' // This also will likely be 'home' for the home page'
); 
$home = get_pages($args); 
?>

See get_page_by_path in the Codex.