Grant is supporting a program spearheaded by the Marie Curie Cancer Care group, which provides at-home services to gravely ill patients, the BBC said.
The "Love Actually" and "Sense and Sensibility" star took up the cause after watching his mother die of pancreatic cancer, the report said.
The charity is asking the government for nearly $12 million to expand its hospice program.
Grant called the Marie Curie nurses who cared for his mother at the end of her life "angels."
"They came in, cared for my mum, chatted -- they made it all possible," the BBC quoted Grant as saying.
"People worry that they are going to be a burden to their family if they stay at home, but if you've got a Marie Curie nurse who can help with everything from the bed pans to pain relief, it really is an option," he said. "If you can have everyone around you -- making jokes, laughing -- as far as they can, having a cozy time, that's really what you need."