Single or double ? If I knew then what I know now I would have insisted on a double mastectomy (this had never been mentioned to me). One reason is the reduction in worry. Another reason is that even wearing a prosthesis I find the real boob pulls the fakie across my chest, no matter how tight I have the bra.
Remember that you can always negotiate with the surgeon re his costs. Are you going public or private ? I have found surgeons waive any gaps if I use private cover.
Hope that helps. Good luck with your pathway going ahead.
Anne