Turning into an executable is compiling as far as C goes. For Python, there probably is something somewhere to wrap a script into a .exe.

For the UI: what matters is the data you generate, not the fluff around it. As the other commenter said, start with a CLI program. You can easily nest several levels of menus if that's your thing. This allows you to have user input. Then for outputs you can do it to a .txt or .md file. Use simple text-based formats. Then once you've got that down you could build a GUI? But tbh I have never built a GUI and I've been programming for 10 years at this point so I can't help you out. There are simple cross-platform libraries you can use out there