Although my treatment was way back in 2006 (the dark ages!!!!), I don't think the basics have changed much. So DON'T PANIC!!!
My treatment started a few weeks after my visit to the oncologist, at my choice, it was just before Christmas and so I started on 2nd January. You may find that your next appointment is to talk about treatment generally, then you'll possibly have another appointment when the radiotherapy team will introduce you to the equipment and also mark with tattoos the area to be zapped.
For the actual treatment, it takes a couple of minutes, if that, so no need to worry about coughing etc. (I had the same fear, by the way, as I had huge problems staying still for an MRI and thought this would be a nightmare.) The longest time is positioning you on the table, I had my arm in an odd position to access the underarm area. Once that is done, you are then left for a minute or so (during which you can cough!!!!) while the team go behind a wall with a viewing panel - they call out "ready", a red light comes on and it is all over.
On fatigue, I didn't really suffer but some people do. I WAS tired and I put that down to the treatment being five days a week for five weeks rather than the actual treatment. It gets a bit tedious and time consuming (from where I live) to get to hospital every day and it was winter which didn't help. I did drive myself after the first session, but most people had an ambulance taxi or spouse.
Anything else, just ask!!! Hopefully some others will reply with their experiences, I know we don't all react the same way.
She brightly finished by saying that as cancer patients are Maladie longue duree anyway, why was I not having the VSL -ambulance taxi?....then I found the health law cannot refuse you it AND the Doctors prefer it.
so my advice would be check your insurance and then sit back and let someone else take the driving strain!