Hello Sam,
The capability for work form has very different questions to the PIP form because it is only concerned with the environment. So the good news is that there is not another form to fill out.
I am not sure about the phone call, my guess is that it could be your work coach just making contact. At some point you are likely to have an assessment call, similar the PIP one, but I would not have expected that to be so soon after completing your form.
Catherine
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
