Got sick... 2 weeks until my first HIM, need help getting back on track

Just jump into the plan right where it is.  Don't over think this......enjoy your HIM, you'll be fine.

Yeah, pretty much.

You're two weeks out from the race.  Trying to make stuff up at this point puts you at risk of injury.  Don't worry, you can do it.

At this point, your fitness is what it is.  Having already been sick, you're health and therefore fitness are compromised, but doing a long ride or long run isn't going to "improve" your fitness and could very well set you back health-wise.  

Now there is a mental aspect to having completed these workouts...Maybe your longest ride has been 43 miles and now you're facing the uncertainty of riding an additional 13 miles beyond what you've ever done...You can adjust this mental picture in the next 2 weeks and still set yourself up for a successful race even without the 50 mile ride.