Even though your friend isn't keen on having her OH drive that distance it may well be the best solution available for her and the puppy.
400 miles each way and nearly all of it on the M6 motorway so there's very little chance of getting lost. We tend to use Travel Lodge Lancaster for our overnight stops as they're dog friendly and, although there's officially a £20 per night charge for pets in the room, we've only been charged this once as cocker spaniels have the knack of melting most receptionist's hearts

Rooms for two people at Travel Lodge are about £40-£50 per night with meals being available at the adjoining service area.
The round trip will then be split into four more manageable sections of four to five hours a day, dependent on your speed, which will allow plenty of time for more comfort breaks for humans and puppy at other service areas along the way.
As I said previously we've done this trip a few times in December and haven't had any weather problems except for one year when there was some fog around the Birmingham area. Nothing to worry about though and, if I remember correctly, the traffic was still moving at 40 for half an hour or so until it cleared.
Your friend could even make the trip into a sort of mini-holiday and it would be a great way of starting the bonding process with the new puppy.
Bob.