You should contact your local surgery/diabetes clinic or even 111 for better advice on that ma'am, I'd say yes, as far as is possible but aren't in any way qualified to give that as advice, so it's just personal opinion.
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.
Thank you both for your comments. I have spoken to my diabetes nurse and she has said that I should self isolate even if my operation doesn’t go ahead. I am going to have an immaculately clean house and “garden of the year” by the end of my isolation!