I can say that I've done a marathon on less :) It was kinda painful, and I sat in ice baths and downed ibuprofen for a few days afterward, but it can be done. Just don't expect a record-setting time. My first marathon was the Big Sur Marathon. It's one that most people (and I only learned this after) train for by doing several marathons prior. So with minimal training, my longest run was up to 18 miles, I was able to complete one of the most difficult road race marathons in the US. Of course, I was hurting after mile 15, and every step afterward was a horse-and-carrot, but it was completed.

If you want to avoid mere survival, I'd strap on a headlamp, some reflective clothing, some gloves and be prepared for some long dark runs. And if you can get someone to ride along with you on a bike, even better.

Good luck!

I'd say 3-4 days of running a week should be enough. I also joined a running club, mostly to improve the run leg for triathlon. But these folks were all runners and we were doing 13 - 18 miles on Saturday mornings. So they talked me into running the Chicago marathon.
I only ran 3 days a week due to the fact I needed to get in swim and bike training as well.
5-6 miles on Tuesday and Thursday and then a long run on Saturday with the club was my
run training.
The good news is that your event it a ways off. So you have plenty of time to ease into higher mileage.
Maybe check out trainingbible.com and look into a training plan that fits your schedule.
Good luck!

I’d say to stick with your plan whatever it is. If you can only run 3-4 times a week fine, but do it! don’t lack of motivation. I think the Paris marathon is in April isn’t? So you have 16 weeks to train. You will do fine if you (again ) stick to your plan. If you don’t have one check their website they should have some for different finishing times. All major marathons post their training plans. The most important session of your runs are the long slow runs, does not matter if you walk or make bathroom stops. I would not do hills or track training. I would not do fartleck or tempo. I would focus only on finishing (finishing strong ) and for that you need the long runs. Try to incorporate one every week. As you know don’t increase your miles more than 10% per week. Long runs help you to tune your mind up and prepare mentally. Start training today!
About cold and dark use the treadmill, or gym. Use your days off to run in daylight. Buy cool set of running gear for cold season. Check your shoes, if they are more than 6 months old I’d buy a new pair now and start use them asap. About you knee is hard to tell, check w/doctor to make sure is nothing risky for you. Don’t worry & enjoy your training. “the hardest part of Ironman (marathon) is not the day itself, its getting to the day�
Good luck