There are basically four ways to talk about the future - will, going to, present continuous, and present simple.
Will is an idea, or a response to to something
going to is planned
present continuous is arranged
present simple is scheduled
"How are you getting to France?"
1) "we will drive there!" - you just had the idea
2)"we are going to drive there" - you have planned the route and arranged for the car to be serviced.
3)"we are driving there" - the car is serviced, the Channel Tunnel is booked, and an overnight stop at a hotel in Rouen is confirmed.
4)"we drive there at 8am tomorrow, the Tunnel ticket is for 12 noon." - you have your timetable.
In your examples, A and B could use present simple.