That decision may be taken out of your hands with the Health Secretary saying that self isolation is one of the options the government is considering.
Unfortunately the probability that non urgent surgery will be postponed is a greater risk.
I wish there was a decent answer, but as kev-w says, it's best to ask 111 or the hospital, perhaps even the surgeon involved. At least the surgeon is likely to be the first to know of planned postponement.
I wish you all the very best.