You can add a consent form at the beginning with something such as “press ‘y’ if you agree and want to start / press ‘n’ if you disagree and want to quit”. You will need to add a keyboard component with the clicks “y” and “n”. After that you can add a conditional loop such as the experiment continues if “y” was clicked and quits if “n” was clicked.
For the questionnaires I added a qualtrics link at the end of my experiment (you can do this in the experiment settings, completed/incompleted URL), the survey tool called “form” in Psychopy is not supported in Pavlovia.