How to get current page id and compare it to looped pages inside the same page?

The current queried page can be accessed with get_queried_object(), or if you just need the ID, you can use get_queried_object_id().

However, while comparing the current ID in the loop to the queried object ID will allow you to skip a specific post, it won’t work well with your pagination, because the page that features the current page will only display 11 pages, rather than the 12 that it’s supposed to.

To exclude the current page you can use post__not_in, like this:

$args = array(
    'post_type'      => 'page',
    'post_status'    => 'Published',
    'category_name'  => 'Football League',
    'posts_per_page' => 12,
    'paged'          => $paged,
    'post__not_in'   => get_queried_object_id(),
);

However, if you have a lot of pages, the performance of this is not great.

All that being said, if you’re trying to create paginated lists of content, organised by category, then this is not the way I’d go about it. This seems like a good use case for a Custom Post Type and Custom Taxonomy.