So sorry to hear this news but glad they appear to have caught it early. Also that they told you quickly and that there is a plan in place that isn't too far away. I can imagine the 12 day wait will still be horrible though. Do you have that person's number, as you could phone every couple of days to keep yourself front of their mind for an earlier slot?
Really good that you are already looking ahead to getting yourself physically ready for the challenges ahead. There is SO much you can do to support your mind and body, and help yourself recover from the treatment. Hopefully it will help you feel a little more in control if you are doing positive things for yourself.
I know you said you live alone but hopefully your doggy will be a wonderful comfort and always give you a reason for a little walk, wven just around the block. And you can always post here as there's pretty much always someone around to offer support or just hold space for you of you're feeling overwhelmed xx