The most useful link I can share is for Flat Friends. Flat Friends is a registered charity that supports women living without reconstruction after mastectomy, due to either a breast cancer diagnosis or preventative surgery. There is also a Facebook page and a closed group.
If you like to wear prostheses then request your free knitted knockers! a UK based registered charity that has been in operation since January 2014, knitting and crocheting 100% cotton breast prostheses for women that have undergone a mastectomy or lumpectomy.
Next up is abcdiagnosis. A web site created to provide information to help you make the right decisions after your diagnosis including information on surgical options.