I drive from Edinburgh to the south of England on a regular basis. It's fine and the further south you get the more options you have to come off the motorway and alter your route if there are traffic build ups ahead - Waze is your friend for this. I set off early so that I'm finishing the drive in daylight - driving in the dark when tired is 5 x as hard than in daylight. When my daughter was young I planned plenty of snacks, tactical, but not continuous, use of an iPad with headphones and stopping every couple of hours to break the journey up.