There is an issue where, when you exit a Codelab, you are taken back to https://scott3142.uk/ rather than https://scott3142.uk/python-programming as expected.
This used to be fixable in app/elements/codelab-elements/codelabs-elements.js as per the README, but since the new update to Codelabs on the Google side, this fix has broken.
The only workaround is to click the browser 'back' button or navigate in some other way.