Hello peaceanddove. I'm glad my post was some reassurance. I just wanted to add that I would reconsider telling your DCs and close family.
Surgery can be quite debilitating and lymph node biopsies are painful while they're healing - I used to say it felt like someone had stuffed angry porcupines into my armpits. And radiotherapy is tiring, can burn your skin and in my case, made me very nauseous, because the radiation field covered part of my liver.
So the chances are you're going to be under the weather for a couple of months and you might worry your DCs more if they don't know what's happening. My eldest was in the first year of her GCSEs when I was diagnosed and I did worry about it distracting her but I felt I had to tell her (especially as at that point I'd been told I would need chemotherapy - I didn't in the end because I was very lucky and it hadn't reached my lymph nodes after all).
I won't pretend my DD wasn't upset but I stressed that the odds were very much in my favour and she would say now that she was glad that she knew what was happening and that I didn't appear to have a mysterious illness. And she did extremely well in the GCSEs so the news didn't affect her work. I did tell her form teacher, on the hospital's advice, so the school would know to make allowances for any extra scattiness on her part.
We also told close family and friends, partly in case we needed help babysitting the youngest, who hadn't started school at that point, and because I think it was comforting for DH to have someone to talk to about his worries. Having cancer is frightening but having a partner with cancer is frightening too.
Tamoxifen has not been that bad. It has thinned my hair (this doesn't happen with everyone and I don't think it's noticeable to anyone who hadn't seen my hair before), thickened my waist (very common) and made me prone to leg cramps - but these can be controlled by regular exercise and drinking plenty of water.
Gosh, that turned out to be an essay. I hope it is some use!