Hi,
I had surgery on the NHS 2-weeks ago. I think I remember first going to my GP about it in either late June or early July last year. So all in all it took me a year, give or take a few weeks. Also I had my surgery delayed so that it wouldn't coincide with exams, and also because the machine they used broke and they had to fix it. I think waiting times will vary depending on were you live and how busy the doctors' schedules are.
Make sure you insist that surgery is done by a plastic surgeon and not any old butcher. That will ensure that the scarring and overall shape of your chest is good after surgery, rather than caved in.
I am not sure if you can keep it off your medical record, that you will have to discuss with your doctor. Also, I was in bed a lot for a few days and I couldn't lift anything for a while - it will be hard to hide that from your family for any period of time if you are living with them. Also you will have to wear a compression vest for atleast a few weeks which will also invite questions. I decided to tell my parents, but not my siblings - they only knew that I had surgery but that I didn't want to tell them.
You can read about my experience here:
http://www.gynecomastia.org/cgi-bin/gyne_yabb/YaBB.cgi?board=8;action=display;num=1155244582Good luck!