Two weeks isn’t enough to become a fish. Two years, maybe, if you swam at least 3 times a week. So at this point you’re in “just get through it” mode. Flanagan’s right–safety first, don’t do it if you’re really not up to it. Having said that, there are a few things you can try which might help.
As mentioned above, don’t focus on the kick. I’d suggest trying a pull buoy, a foam thing you put between your legs which helps keep your body flat in the water. Don’t kick while using the pull buoy, and focus on long easy strokes. You’ll actually go faster by swimming efficiently rather than harder.
Extend and stretch when your hand goes into the water, like picking an apple you have to reach for. Hand should be out in front when it goes in, not crossing over your head-to-toe centerline with bent elbow. Pull with fingers together, hand under your body not out to the side. Extend fully before your hand comes out of the water.
Develop “water feel” and a good streamline position by doing some push offs–push off the wall and see how far you can go underwater. Hands above your head, stretch, point the toes. Ok, there’s no wall to push off in an open water swim but this really helps beginner swimmers, imho.
Do 600 or more yards in the pool without stopping at least a couple times before the race. It’s not like running, where “if you can do a half in practice, you can go the distance in the race.” You gotta be able to do it in practice.
Race day, make sure you’re at the back and of the wave and off to the side. Don’t start near the front thinking you need all the extra time you can get. You’ll get run over. Some races let beginners use those noodle deals, and/or have a special color swim cap so the lifeguards can keep en eye on you.
Longer term, keep with it. Do a clinic or take a class to work on technique. Swim a few times every week if you can. Just doing the yards will help, but technique is everything.
Good luck and have fun!