How I'm training at the moment

So now that I've explained why I'm training for a half marathon the next questions that comes to mind is probably how I'm planning on doing that.
I'm known as someone who doesn't do things half way and this is no exception. At the moment I'm walking/running three times a week and go to the gym another three times a week. Overall that makes for some work out on 6 out of 7 days (pretty good I'd say). The gym is mainly for strength training to built some muscles but I usually also do some cardio on the bike or the cross trainer while I'm there.
The running is the tough part for me. At the moment I do just under 5km in about 40 minutes of which I'm actually running about 21 minutes while the rest is walking (I'm doing a walk-run-walk-run ... sort of rhythm). The goal is to increase the running time. On average I run about 30seconds more every week and I hope that will increase faster the fitter I get (and the more weight I lose).
I'm planning to keep this up for another 4 weeks and then start a 'real' 12 week half marathon training programme during which I will slowly increase the distance (I'll probably write more about the training plan once I've started it). That should get me fit for the event on the 31st of October. That's the theory - something tells me the reality is gonna be very very tough. But I am fairly confident that I can do it if I keep up what I'm doing right now - as long as I don't get injured. Doing this much exercise relatively sudden and while being overweight comes with quite a few risks. If I would get injured within the next 4 months and had to take a break from exercising, I probably would have a really hard time to get started again. That's why I'm being careful and try not to do to much at once (not always easy, I tend to get very impatient with myself). I do proper stretching before and after working out and stop when I feel any pain. So far I've been alright - fingers crossed.