Remi is a GUI library for Python applications that gets rendered in web browsers. This allows you to access your interface locally and remotely. There is also a drag-n-drop GUI Editor. Look at the Editor subfolder to download your copy.
No HTML knowledge is required, Remi does it all for you automatically.
Looks fairly straightforward to use, provided that you start using it at the beginning. I don't know how easy it would be to retrofit existing code.