OK, OpenGL, sdl, directx and so on are GRAPHICAL APPLICATION PROGRAMMING LIBRARIES NOT GUI's
A GUI is a collection of buttons, sliders and other things that you use to access function in an application.
When you start a game and get a list of options that say for example, start, load, reset, options. That is a GUI its an interface for you to use the application.
If you are looking for a Graphical API then i would start with something like SDL.
And by the way OpenGL can be used with python.
If you want a GUI library then try WX Widgets its very good and pretty easy to use.
But i think that you need to stick with learning a language before moving onto something like that.