The August Splatoon update, which released in North America on August 4 and brought Splatoon players ranked battles, a higher level cap, in game parties, new gear and weapons, new music, and a whole host of other changes and improvements to the game, will be available for UK players to download this weekend.
The update, which was promised to us before Splatoon even launched, finishes the free game as a service model that the title was launched predicated on; that said, Nintendo has promised that additional content will continue to come to the game, for free.
Splatoon originally launched on May 29, with just five maps, no ranked battle mode, and limited weapons and gear- over the next few weeks, Nintendo made good on its promise, and expanded on the game. This update completes Splatoon, as far as launch standard and promised content and features go.
Splatoon is available right now, exclusively for the Wii U.