I dont think that there should be any problem with the surgery later.
I tried working out for around 11 years but without success.
Some advice to you.
DOnt over work your chest muscles in the hopes of losing the fat. the muscles will develop pushing the chest further out. Will give a bulkier look. Also after surgery the chest muscle will be very prominient since it has been worked the most so most developed.
What i read after surgery is that HIT cardio, that is High intensity cardio helps to burn the adipose fat tissue. The major component of the fat in your chest. You can do regular cardio to start of and when you are in perfect shape with a fatty chest you can start HIT cardio which should help you burn some of the adpose tissue.
This entire process will not help out with the gland behind the nipple or the glandular tissue.
Hope it help.