Gary Barlow, Chris Evans, James May and Brian Cox have set off from Lands End in a pink Rolls Royce raising money for Breast Cancer Care.
The challenge will see them driving from Land's End to John O'Groats in a bespoke pink Rolls Royce Ghost.
They want to try and raise £1 million in 24 hours.
The four celebrities will stop off in Bristol as part of their trip.
More top news
The creative industries across Bristol and Bath have received £46 million to create 'new experiences and boost productivity.'
A service in Plymouth run by the NSPCC, which helps prevents online child sexual abuse, is expanding.
Bristol Water is urging people to stay safe and not swim in the water at spots like Chew Valley or Cheddar Lake this weekend.