You don't need to have an in-depth knowledge of Tcl to automate running Simile models using SimileScript. Generally if you have some scripting or programming experience you will be able to adapt one of the examples scripts (in the "examples" subfolder of your Simile directory). However, to understand fully what's going on in the examples you will need some more information on Tcl.
Furthermore, Tcl is a powerful language with many extensions. Powerful enough to be used for application programs, indeed the Simile user interface is written in Tcl (with Tk the graphical toolkit). If you wish, your SimileScripts may be far more powerful and complicated than the simple examples included with the Simle installation.