Six weeks is not a lot of time to prepare for such a distance, even if your goal is just to finish. Of course that all depends on how often you currently get in runs each week and how long you've been running. If you are simply planning to walk or some walk/run combination you'll more than likely be able to finish, yet to consider running the entire distance may be a lot (You'll certainly be very sore.). I am including a link to a half marathon walk schedule that you might use to gauge your fitness and maybe help you decide: http://www.halhigdon.com/halfmarathon/walk.htm
Best of luck, which ever choice you make!