Chrissy
Welcome, and sorry that they have found cancer cells. Waiting is the worst part of all this and something we all do not like doing.
It will be good to talk to a breast surgeon on Monday and she will set you on the right track.
Regarding your question about Arimidex. - There are lots of different kinds of breast cancer which you will learn all about later. Arimidex is only for Post menopausal women (my menopause was induced during chemo when I was 36 years old) and only if your cancer tested positive to estrigen, I had a bi lateral mastecomy. Not all cancers are positive. Anyway until the surgeon knows what type of cancer yours is, you are getting to far ahead of yourself. There are so many different treatment options, so try not to think that far ahead until you know what you are dealing with.
Great that you have good support.
Tanya