I am disabled and when I lived at home I had to contribute with my disability money and use the rest for my expenses .
When I left home I was able to claim for the full cost of my rent, + universal credit, and the LCWRA component of universal credit, I also have PIP.
if you are struggling with money and your adult children living at home get PIP get them to apply for their own place so that they can have enough to live on.