So Google UK is now allowed to use everyone's photographs (not just thumbnails) and use those photographs to sell ads next to it. How is that right ?

It only applies to orphan works but you can easily and in an anonymous way strip out the metadata.

And companies like Google could take it one step further. All they have to do is start a LLC in the UK for the Google image search part of its business, go to Twitter, Facebook, Flickr, ... take all the photos, strip the metadata, say it was someone else who must have done it, make a lot of money.