Well... from the experiences of my son and husband, I know that the odds are much greater than 50/50 it's going to happen again. My son had almost constant drainage until the surgery. My husband has less frequent flareups, somewhere in the neighborhood of every 3-4 months; but they aren't always such awfully painful flares. That's why he has chosen not to opt for the surgery... because he can most times just live with it until the draining starts.
The cyst sac itself will remain until it's removed, and there will always be a bit of infection inside the sac, because antibiotic medicine cannot enter the sac to eliminate it. When the bacteria count rises high enough again, a more active infection will start... and there you go again. You can just wait and see how it will go for you. Maybe you are more like my husband; maybe more like my son and just want it to go away for good.
I guess that "Manchester" is in England? I know your health system is much different there, and it sounds as if your primary care guy doesn't know much about this problem. If you'd like to get it over with and go the surgery route, you should ask for a referral to a general surgeon or colorectal surgeon, as cj1986 mentioned above.