Emily,
Great news on the surgery date. It is usually the "waiting" that is the hardest.

Should you be worried? Why? What's the alternative?
Also, you have educated yourself, you have listened to other MMers stories and know it is different for everyone. You have been very thorough and asked all the important questions. You have prepared yourself. You also have a very positive attitude and I believe attitutde is everything. You know that old saying "Is the glass half empty or is the glass half full"?
You know the risks with and without the surgery. You also know the risk of everyday living . As others have said, any of us could get hit by a bus. You hit it on the nose when you said the surgery is out of your control so why would you worry about something for which you have no control.

You also have doctors who are familiar with MM. That's a plus in itself.
If you think you should worry, just exactly what would that worry be?
You probably have no answer because you have done your homework and done it well. You have removed the unknown. The only posssible negative I see is that once you have the surgery and can once again do the engineering math equasions, you might have to go back to engineering!!
Hopefully, you won't have to be concerned about your dreadlocks either. Hopefully, it's like in the States, wherein they only cut the hair where they have to make the incision and it is usually in between hair above and below the incision. So if you have long hair, it will fall over the incision and cover it up. Yeah!! More good news and one less thing you have to be concerned with.
You keep the positive attitude and you will do just fine.
My motto: One can get busy living or one can get busy dying. It's a choice. It 's obvious to me you are busy living.

You will continue to be in my thoughts and prayers.
Keep us posted. I suspect Em will let us know how you are doing.
Hugs,

Lore