QT Designer is different from pyqt. QT Designer is the Wysiwyg editor that creates .ui files that you can either compile to python code or import into the python code. Pyqt is a library / module for writing python code for qt.
To use qt creator with pyqt, here is the documentation
Qt is excellent, but honestly I think it it more suited to C++.
I have found the TKinter is actually extremely powerful, fwiw.