Being awarded the grant does not automatically affect your PIP. There are people who work and are awarded PIP. The question is whether you still fulfil the criteria for PIP if you are going to be working.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems
Just so you know, I have recently spoken to an assessor on behalf of my daughter. She has epilepsy (sometimes without warning) and is terrified of going to the station for the train to work. I explained this to the assessor and said that I am in the process of apply for Access to work. He still awarded her lower rate care and higher mobility.
As Bis said it depends on what and why you are claiming it.