You can add more subscriptions to uBlock Origin than are listed in the filter page. It is easy to add subscriptions from this page:
https://adblockplus.org/en/subscriptions
By scrolling to the bottom of the filter page, you can see the new filter subscription that you added.
To block a site completely, you can add the hostname to a personal blocklist that you can add to "My filters". That list takes wildcards, so you can block a whole domain, if necessary.