My Mum prepared me for being flat chested, as before child birth my boobs were 32AA, just like her. However, unlike her my boobs ballooned and did not shrink back. I now have 34F boobs. But I am taller and though slim, have a broader frame, so my boobs have not had a major impact on posture and back problems. I do have problems with buying a bra that fits well. I have only found one style and make that fits and yes it is underwired, which is now causing problems with rubbing and catching on skin tags.
In the 1986, I had a tummy tuck and muscle repair after 2 large babies close together. No amount of tummy exercises could repair the damage. I looked 5 months pregnant when my son was 5 months old. In the ward, there was a lady having a breast reduction for the same reasons as you. This was all done on the NHS, but I suspect that you will have to pay with the financial climate as it is. Do check as you want this done for legitimate medical reasons. I am so grateful that I was able to have my op through the NHS, but we would have re-mortgaged the house, if we had had to seek help privately. You can't put a price on the physical discomfort and distress. Go for it!