(I've never had to deal with rail replacement buses before).There's engineering work in the Coventry area, tomorrow, so, yes, there will be a rail replacement coach/bus for part of the journey.
More often than not, rail replacement services are NOT accessible. If that's the case the staff in attendance will provide an alternative method of travel (which is usually an accessible taxi).
Just noticed I got my days mixed up too. I meant a week on Sunday (26th).