Hi @theartofhappiness I haven't had a total duct excision but I have had a breast/nipple surgery to remove an intraductal papilloma (basically a growth in the milk duct causing nipple discharge). I think my surgery was a microdochectomy (removing a single milk duct).
I don't know how much different the operation is, but from looking at the NHS document linked below the total duct excision seems pretty similar to the microdochectomy. For mine, the surgeon explained she would cut around half of my areola area and remove the problem duct. I still have a small scar that goes halfway around the areola but it's not that noticeable because it's around the natural line of the areola in the first place.
The hospital will no doubt give you all the instructions, but from what I remember I couldn't eat or drink the from midnight before the surgery because it's a general anaesthetic. I also had to be naked under the surgical gown which I was a bit disconcerted by since it was just the nipple, but I think that's maybe standard for general anaesthetic.
For post-surgical recovery I had the usual resting instructions for post general anaesthetic, and not to exert myself or lift anything heavy. But there were no issues around moving my arms. I live by myself and didn't need any help except for the requirement to have someone collect me from the hospital. It was a day surgery. The stitches were localised to the nipple area and didn't affect the rest of my breast. When the surgeon followed up with me a couple of days later she told me I should be showering properly by that point already! I was worried to get the stitches wet. I followed all the instructions and it worked out fine.
I was anxious about it beforehand, but the surgery went well for me and I haven't had any problems since with nipple discharge. There had been blood in the discharge which is what prompted the surgery. The surgery healed fine but I have occasionally had tenderness in the nipple area a couple of years later, which I think may be hormonal/perimenopausal and was combined with breast tenderness in general.
I am in Canada (although I am British so know the NHS) so things might be a bit different, but from the NHS document it looks very similar.
https://www.swbh.nhs.uk/wp-content/uploads/2012/07/Breast-duct-excision-ML38861.pdf
Hope that helps a bit! Let me know if you have any questions and I'll see if I can help :)