5k

Like the other poster said, if you're already doing 30 minutes on the treadmill you must be pretty close (obviously this depends on your speed, though). If you were starting out fresh, I would recommend that you do a Couch to 5K program but you're clearly much closer to 5K than to couch. You could try downloading the app (it's free) and starting at say week 5 or whatever you think is feasible (there's 8 weeks) and then building up to the 5K. The C25K basically has you alternate walking and running, starting out in week 1 with you walking more than running, and eventually flipping this until you're running the whole time. It's 30 minutes a day three days a week. And also like the other poster said, assuming the weather/climate where you live allows for this, I would definitely advise practicing running outside - some find the treadmill easier and others the road but it's important that you be accustomed to running on the road because it does feel different. Good luck!

If you can't run outside, you may consider running on ab1% incline. It will help prepare you for the 5k, since roads, no matter how flat they seem, are not completly flat. Good luck!

Agree with all that has been posted. Road doesn't move for you (I have the opposite problem, I can't run on a treadmill because i am so used to running on the road) and not all roads are made equally. I will say this, if you don't already have good running shoes, get some and stretch race day. I will also say some 5ks provide maps of the courses so this way people know what they will be running on, so if you can get one, do it.

Most of all though, just relax and have fun on race day (I have my sixth 5k coming up next month) and you never know, you might end up running another!!!!!!!!!!! Good luck!!!!!!!!!!