All the best, I hope they don't get concerned about your BG. I have heard of ops being postponed because of BG concerns.
I had a laparotomy as the result of a failure to diagnose a burst appendix and peritonitis (my first words to GP were actually "I think I have appendicitis, but don't have all the symptoms"). Luckily I was "fast tracked" and after a consultation and a scan and a phone call to confirm I had a lump, seven weeks later I had the laparotomy.
They were concerned about my BG on the morning (10.2) but had no choice because they still weren't 100% sure what the problem was. Luckily I had previously been prescribed antibiotics because the GP thought I had an infected gall bladder (unusual for 60+ year olds to have appendicitis), it served to keep the peritonitis under control. The anesthetist was brilliant because he just had me hooked up to the necessary to monitor and control my BG during the operation.
Hope it all goes well!