Firstly, I am so sorry you have joined the bc club, but you will find so much support and help on this site, from so many girls who have been through it all.
Take advantage of the 6 weeks before your surgery to do things like see your dentist (the last thing you want to do during treatment!) and overhaul your kitchen so that you don't have to reach up for items you use a lot. Stock your freezer with pre-cooked meals, and give your friends a roster to fill out themselves on who can help with cleaning, children, school runs, shopping etc. Perople often want to help and don't know how.
For hospital you are best with front-opening pj tops - easier to check dressings, etc. and get out of easily for showers. Two small pillows for tucking under your arms at night really help to keep you comfortable on your back after surgery. A notebook helps to keep track of future appointments/physio instructions etc.
The operation varies from person to person, but I found it surprisingly pain-free - the post-op meds really work, and in a day or two, panadol does the trick. Have you arranged for the free bra from Berlei yet? You won't wear one at first while you heal, but it will be useful for work until you get organised with your prostheses. I don't know what work you do, so can't comment on how long it would take to go back. After 2-3 weeks of physio exercises you will be surprised at how much better you feel - some you do every hour, but they are worth every minute of effort.
All the very best for your surgery. Stay in touch. Big hug, Michelle x