Not many GP's are trained to do it. When I had mine put in I had to have it done by a gyno. It cost $120 for the procedure and $30 for the Mirena. We have a Gyno who visits our Mediacl Centre once a fortnight.
I had mine inserted while still BFing and it didn't affect feeding at all. I felt no pain at all getting it put in, although some women do. Once it was in my AF was very, very light and sometimes no AF at all. It was the perfect contaception for me, up until about 18 months of having it in and I started to get cramping and continuous spotting/light bleeding so I had it removed. I was worried it had moved as they couldn't find the string, but it hadn't moved at all, the doctor had just cut the strings very short...he just needed an extra long tool to grab the string to remove it, LOL. I also had to have the Gyno remove it as none of the GP's Medical Centre could do it, there was no charge for removal.
It really is one of those "won't know till you try" contraceptions, and it's easy to get it removed of you have any problems.