You can always have your single, have your treatment then look at having the other removed with reconstruction at the same time. The most important thing is to tackle this. I had mine both off with tissue expanders inserted. I didn't require radiotherapy which can make reconstruction more complicated.
Your breast surgeon will be the best to advise all this. I hope by now you have your GP appointment. Sonetime initial pathology shows cancer and the type takes additional testing. Hopefully by now your GP has that info.