i've run 4 marathons and a few half and unless you've been running 10 milers regularly for fun, i don't think it's advisable to train for a half marathon in 6 weeks! like, if you only run 1-2 miles at most, it's not enough to give your body a chance to adjust. usually you spend a couple weeks building up your mileage, then you have a week where you taper off.... so it can take 4 or 5 months of training.
which reminds me, i also signed up for a marathon in october and really need to get my a in gear training-wise...