Lync 2013 to become Skype for Business this month.
The Windows client for Lync will presumable be updated this month to Skype for Business as part of the regular Office 2013 updates. The update will add new functionality to Lync (Skype for Business) but will more importantly come with a slightly updated (and more Skype like) interface, acording to this blogpost. You may want to considder if you wish to control the deployment of this new client/layout as to not totally confuse your users in a corporate environment.
You should also be able to force a “Lync 2013” look-a-like look for Skype for Business, read more here;
You can basically create a new “GroupPolicy Preference” that blocks the SkypeUI, and this sounds like the right approach as this would work from first launch where as the server patch will “only” display a user dialog offering users to switch back to the LyncUI.