I cannot edit my previous PDP

If you are undertaking your first appraisal since your CCT, but you are not able to review the PDP from your last appraisal or final stage of training, then you need to follow these steps to be able to 'activate'  the PDP Review section.

First click into Past Appraisals and then untick the box next to the statement This is my first appraisal. 

Go back to your Appraisal overview or click on Portfolio again, and you will be able to review the PDP and leave reflections.