You'll be fine. Have you had training?
I'm not the type to get frozen up with nerves, but 5 minutes before my MOD1 I was starting to feel quite twitchy. Also a guy I went up with me passed before me, so the pressure was on.
The MOD2, even though it's the more difficult test, feels much easier because you're a lot less nervous about it. In fact I wasn't nervous at all throughout the who thing. Actually that's not entirely true but that was done to the gale force winds I was doing it in!