A bus, carrying pensioners who were out on a day trip, collided head-on with a timber lorry on a country road near Puisseguin in the Gironde wine region, east of Bordeaux at 7:30am local time.
France's president, Francois Hollande has described it as an "immense tragedy".
It is the worst road disaster in the country since 1982, when 52 people died.
Sally Davies, from the Chaplaincy of Aquitaine, told Premier's News Hour: "We can try to assist in any way we can, but we are still receiving news of the situation.
"Our love and prayers go with all of these families and we are trying to use our ecumenical contacts to see if there are any English people involved on this coach trip, so we can help."
She added: "We are all in a really big state of shock. A lot of people are just dumbstruck really."
Both the bus and the lorry are said to have burst into flames on collision, at what local residents have described as a notoriously dangerous bend in the road.
Speaking at the scene of the crash the French Prime Minister, Manuel Valls, said 42 people died "in atrocious conditions in this bus, which was in flames after a very violent head-on collision".
Sally Davies said the tragedy would be marked at Chaplaincy of Aquintaine churches this weekend.
"I am sure that all intercessors who do prayers this Sunday will have the thoughts of these families in their hearts throughout all of the chaplaincy."