Hospitals prioritise CS's all the time, according to need - a CS where the baby is in acute distress will be given priority over one for maternal distress, for example, no matter how distresssed the mother.
CS's are quick operations, usually 45 minutes or less in theatre. As QTPie says, the list is monitored and assessed all of the time - very few women who go in for a planned CS FOR ANY REASON, including breech, have their op at the scheduled time precisely because emergencies come in and are dealt with first.
This is NORMAL, it is the way hospitals work. There will be enough down time for an elective CS somewhere along the way in 24 hours. Yes, it might mean a wait. But that's fine.
If you have been told you are having a CS, the consultant has signed this off, then you will get your CS.
If you are in the tiny, tiny, minority of women who have a very rapid labour, and things progress too quickly to get you to theatre, then those are the only circumstances where you might not 'make it'. But that's not so much an issue of scheduling theatre slots, those women can give birth in a car/ambulance/kitchen floor.
Don't worry about it. Get it agreed you don't want a trial of labour under any circumstances, and they will make sure there is no unreasonable delay. And don't listen to scaremongers. They should have better things to do with their time.