I am currently working on a small Python script that is running on my local server. I want to create a Ui for it with Qt because i work a lot with qml. Is it possible to make a PyQt web application that i can access through my browser inside my network?
No.
Web apps and GUI programs are completely different beasts.
Usually,

GUI apps require just Python interpreter, your scripts, and proper GUI libraries. You access then from within your machine's operating system.

(Python) Web apps require Python interpreter, running Web server software  and making of HTML/Python web pages instead of  GUI components. Web page access happens (typically) from a browser environment, which might be local or remote.


While it is not impossible that somebody could have made libraries for showing Python GUI interfaces over the Web,  it wouldn't make much sense, because it is usually much easier to just use some remote desktop software to access your machine and use native GUI.
Is it possible to create a PyQt web application?