So sorry Liz, that really sucks.
I just don't get it, the NHS are supposed to be all for prevention rather than cure (think: Fit for Life) yet, they aren't addressing the needs of those of us for whom this message has reached us too late. In your case, I would definitely reapproach your GP and maybe talk to your MP - explain that the scarring as a child has always had a negative affect on your body image and was a direct contributor to your weight gain in the first instance (even if this is bending the truth a little). Say that you've followed all medical guidance and have been under medical supervision throughout your weightloss journey. Explain that the weight of the excess skin to your stomach and breasts is making the scarring worse and causing you extreme discomfort in your day to day life and emphasise all mobility issues (e.g. when walking, lying down, etc.). Explain how this excess skin harbours your daily routine and prevents you from leading a normal life.
There has to be a way around this, I hope you find it soon. X