Will they be running buses that early? Yep. Buses start running at 6:30. With a group that size, I would be out at the MK bus stop by 6:30. That way, your chances of all getting on the same bus are better. Yes, you may have to wait a bit to enter MK but at least you'll be there. And if you have to split up and take different buses, then you'll have enough time.