Parkrun is the best.
I am very lucky, where I live in Western Australia there are many parkruns near me. The first time I walked mostly and took about 47 minutes for the 5k. My best time is now 38 minutes. Unlike c25k I haven't ran for 20 minutes without stopping to walk, about 14 minutes is the longest that I have managed. I have invested in a heart rate chest strap and Garmin forerunner watch so I can monitor my heart rate and keep at a sustainable level.
In my opinion that's much better than following c25k and pushing myself too hard and getting exhausted or injured.
I am 20kg overweight and just stopped smoking after 30years of a pack a day. Also I'm taking tablets for high blood pressure but I seem to have avoided any serious health issues from my tobacco habit.