Hi Kim,
This prob not the best advice but I Had a fairly bad cold start the day before mine, I was gutted as that’s just my luck, it was the only time I could have surgery for another year so I rummaged in the medicine cabinet, took garlic tablets, sudafed, drank loads of water and when I woke up was fine, i had a slight sniffle but managed to hide it well and had my surgery as planned. Was fine! Think positive and you’ll feel much better 🙂 xx