It's natural to be nervous - I had a mastectomy, not a lumpectomy, and a clearance and I can honestly say that I was virtually pain free. I was at the Epworth, was plied with painkillers, but really didn't need or use them. But everyone was really attentive and determined I would not be uncomfortable.
My mobility in my affected arm was good right form the start - this can vary, best to do the exercises (you will be taught how) as soon and as often as recommended. I am sure others can add their tips about looking after yourself in the days following. Drains are usually the biggest pest - easy to trip over when they are in, and everyone wants them out as soon as possible, but your medical team will be looking to ensure you have no side effects that can be avoided, so best to take their advice. This is a good step towards feeling cancer free, very best wishes for Tuesday.