Patch 1.8 is already available for download. Launch is tonight. This is a bulk patch made out of several iterations. Release is scheduled already in March.
You can download the Common Test only through the WGC.
If the Common Test is already installed through the WGC, just update it.
If you have WGC, but there is no CT client installed, just use this hidden code in the game center itself:
In the WGC, on the main page, click “Install the game by code” and after entering the code itself, everything will download from scratch.