PIP is not a means-tested benefit nor is there any restriction on whether you work or not, however, there will be questions raised about how you manage your apprenticeship and still have the restrictions that you think mean you can receive PIP. As a silly example; if you are doing catering it may be difficult for you to score for Preparing and cooking a meal, you need to head these arguments off when you claim don't allow those assessing you to make their own assumptions.
Have you had a look at our PIP Claim guide, follow the Guides link at the top of the page.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems