What changes when my partner who has been on my esa claim starts working

I added my partner onto my ESA claim when we moved in together and he was not working at the time however during the last few days he has been offered a job that is totally set up as a subcontractor and means that he is self-employed and I have to tell the DWP and get him removed from my claim and was advised to get a application for claiming PIP already since I am not well enough to get work myself and I am entitled to get this so I have no idea what I have to do to tackle this situation? Should I inform the DWP about my partner going back to work with no idea how much he is going to be earning yet and then apply for PIP after all these things are sorted or do I apply for PIP assessment to be posted then give the details of change in my ESA claim when I have requested the PIP ASSESSMENT and finally would that mean I have to do a fresh claim to accommodate the change in circumstances and have to get a different kind of benefits all together?