Well after a bit of better searching i found the answer,
function my_enqueue($hook) {
if ( 'settings_page_data-layer-management' != $hook ) {
return;
}
wp_enqueue_script( 'my_custom_script', plugins_url( 'js/dlm-window.js', __FILE__ ));
}
add_action( 'admin_enqueue_scripts', 'my_enqueue' );
to explain just incase anyone has this issue.
what i had earlier was a ‘front-end’ hook which is just wp_enqueue_scripts
for a back end, you need to use the admin hook admin_enqueue_scripts
for your add action.
Next was trying to find the correct page hook. Luckily wordpress being helpfull in ports a $hook into the function, a simple if statement can then be used to determine which page to run the script on.
if you have problems finding your plugin hook, simple echo $hook
to find out what yours is.
full documentation can be found here:
http://codex.wordpress.org/Plugin_API/Action_Reference/admin_enqueue_scripts