Coach trip when a baby is 12 weeks?

ok my brother in law has offered me a week down at his house as a break from my partner since due to his lack of help at home we are arguing a lot. The only problem is i can only afford to travel by coach as the train is �153 one way and I do not have a car. He lives in plymouth england n I live in glasgow scotland so its like a 12hour journey? is it ok to take a baby on a trip this long (he will be 12 weeks when im planning to go) or should i just turn down the offer? I really do need the time away and i get on great with them its just the trip there thats bugging me.