Hi Mattie,
I also am a patient of Prof Hunter's. I had a peri-anal fistula just before being diagnosed with crohn's.
I had surgery to put a draining seton in the fistula straight away. The surgery itself is really nothing to be frightened of, it was really quite easy.
Soon after I discovered Prof Hunter and went on the elemental diet, and it was during this time that my seton was tightened up so that it became a cutting seton. I found this part quite painful I have to say, and my crohn's started to flare up again during this time. I'm not sure if it was a reaction to the cutting process, or the pain, or the fact I had stopped taking antibiotics about a week before. However, about a week after that I was seton free, the fistula tract had closed, and I have had no problems with the fistula since, and two years have gone by. All in all, from having the initial surgery until the tract closing up was a period of 3 months. I did mention that the crohns flared up when the seton was tightened, and it took a month for things to settle back down. Every case is different of course, but since your crohn's seems to be in such a solid remission, I don't see why the surgery shouldn't be successful for you also...