I have a friend who has a lifelong debilitating illness. He used to get disability allowance. Now he doesnt because some retired gp who asessed him said she had never had experience with his illness and therefor didnt think it could be as bad as he made out. (This was said in front of a cab witness!) Nurse who also assessed him made several suggestions about how he could work around it and get a job all totally ridiculous, she was totally clueless as to what his illness was.
He now has £70 jsa to live on, has to get himself to regular hospital appointments and treatments in hospital, feed himself (he has a restricted diet due to condition) pay his bills etc on that money. He can only afford to heat one room at a time in winter and goes without food sometimes as he cannot afford the right food. His parents are retired and on pensions but are buying him food and paying petrol for his car to get him to hospital appointments.
Both he and the staff at the job centre know he is never going to get a job he can hold down due to the unpredictability and severity of his illness and they told him he isnt the only one wasting his own and their time every week. They are disgusted with the system that preys on the vulnerable.
If he misses 'compulsory' tutorials or meetings due to his illness incapacitating him his jsa is 'sanctioned' until they decide he has proved he couldnt go.
Some people will be ok on benefits depending on thier ciurcumstances but others are dumped by the wayside and left to struggle. My friend has had one trip to the food bank but they are only allowed one trip! (and they have to be referred by someone!)
The whole system is a tragedy. People have died after the assessments have cut them off, people cant afford food, heating or electicity to keep their meds cool, people are housebound as their cars were taken from them, mobility allowance stopped.
Your relative might be in for a shock some day.