Hey I was exactly the same, terrified! Not knowing what to expect etc..
You just get a canula put in n have to wait half hour then have the stuff injected and it only lasts two minutes, the test..then wait another half hour n they see the difference, I won’t lie. It’s not a nice feeling having your heart put under stress but just breathe through it n you’ll be fine, honestly it’s not bad xx good luck 🤞