I saw my lovely breast surgeon today and said I was letting go of the stress of worrying what the aftermath of the operation would be like because there was no way of knowing. He said that was the right thing to to, that I had to let it happen, much like when you have a baby, and ride the emotions as they come, rather than plan for them. Someone here said "ride the emotions" too, so I reckon it's pretty sound advice. He said to be 'floppy'! Much like a drunk in a car accident, they get injured less because they don't brace for impact!
He also said that he thinks I'll be fine, but if I'm not, he'll take care of me, that they've got me. It was very reassuring.