disabling menu on static front page to create a splash page

Hello,

I am an adult blogger and I need to make my blog have a splash page that one must click enter or leave on. I have a static front page, however I cannot come up with how to disable the menu off the front page and adding a second button for the viewer to leave if they are not of age.

I am using the theme “Sydney” on wp 4.3.1

Thank in advance!