Hi Danielle,
I had a cold start the day before, so I just took everything I could find to stop it: garlic tablets, sudafed and paracetamol. Next day I barely had a sniffle but just pretended I was ok and everything went ahead!
I’d say if you feel horrific or very ill / congested it wouldn’t be safe to have the op. Just boost your immune system and you’ll be fine.
Best of luck 🙂 xx