Welcome @RL and ask away.
if you look at the discussions in the right hand menu, you will find a lot dealing with chemo and other treatments you may be facing, that will help you in the lead up.
I too went through lumpectomy and sentinel node removal but also had to have a mastectomy after pathology results came back with more advanced cancer.
I am now, just today, finished my last radiation, having also done chemo.
Hope we can smooth the way a little for you just a little.