Regarding reconstruction options, have you joined the Breast reconstruction online group here? The ladies in that group and on Reclaim Your Curves website have a wealth of experience to share. Reclaim your curves hold regular get-togethers where you can talk with other women who are thinking about or have undergone breast reconstruction.
I'm not sure why schools would prefer their teachers to take the term off that they are going through rads? I'm not a teacher but returned to work after 6 months of chemo and three weeks into my five weeks of radiotherapy. In retrospect I did go back too soon. Everyone has a different experience but two weeks in I caught the office cold (immune system not quite recovered from the battering it has received)and the radiation skin reaction kicked in. Too uncomfortable to wear anything that would be suitable for my workplace. I had another month off work. I was all prepared for the fatigue to hit towards the end of radiotherapy it didn't happen for me. The oncologist did emphasise that it would take time to recover after surgery followed by chemo and then radiotherapy. Go with what feels right for you and be prepared to change your plans as you need to. All the best with it.