Take a look at the Pink Hope website.

Welcome to Pink Hope, we are an online community that provides accredited information and support for young individuals who are at a high risk of Breast and Ovarian Cancer.
There is loads of info on this website, and their online community might give you some pointers re finding even a GP in the first instance who will take your request seriously and put in some time and effort to give you a referral a) for genetic testing, and b) to a breast surgeon and good plastic surgeon so you can discuss your mastectomy and reconstruction options.

It's important to note that newer & more sophisticated screening techniques like MRI are now funded under Medicare for young women with immediate family history of BC, so it's important to understand all the options - regular screening, preventive treatment like tamoxifen, as well as the fullness of what surgery with or without reconstruction entails. Then and only then will you have the info you need to make a decision on this scale.

I had a unilateral mastectomy and reconstruction after being diagnosed with breast cancer at age 37. I had it done in the public hospital system by an excellent surgeon (widely thought to be one of the best if not the best in the state) - I'm not sure but I think he may also do preventive breast surgery too. So explore your public hospital options because reconstruction esp can be very costly in the private system, health insurance companies are appallingly stingy in this regard. Feel free to PM me with any questions you have either now or in the future.