Dena,
I am a Penguin! MfM plan truly works. I am proof!
You can do this. The thing is that you must begin putting in steps now. Do some building of a base to the best of your ability. Get out take steps, do some cross training--whatever you can do to move and get some strength and have fun doing it.
As you feel you are able, start to work a little more, not necessarily length of time of your workouts, just in what you are asking yourself to do. The trick is to push yourself, but not hurt yourself.
-which plan you used to train
I started in 2005 using the walk trying to see how fast I could push that. Then I started to throw in a Wog (I call it a Wog=not walk, not jog style). The WISH Walkers thought to try to shoot for a 15 minute per mile pace. That would allow for some extra time to stop for pics or potty. Just those couple years ago I couldn't run from one mailbox to the next in the development. Now I find that I am able to push and am going a bit faster.
-what you actually ended up doing out on the course
I pretty much walked all the water stations. I din't follow the walk/run or run/walk to an exact minute on the course or in training. I do what I am able and pay attention to the pace so I guess that I'm not following the program exactly. I'm still on the slow side, but for me I'm faster than I started. The back of the pack gets the medals same as the front of the pack.
-did you trust that the highest training day was still a couple of miles less than the race
Oh that is always the worry. I didn't feel I needed to do the entire distance before, I wanted my first time to be at the event in WDW. Be comfortable that you will be able to do this if you build a base now and continue with the training weeks as you follow the schedule. My first year I followed the program mileage and it did work for the half. The second year, my first marathon, I added extra mileage for the long run 22 instead of 20 and it was something I mentally needed. This last training I did 20 as the program required and I made it fine.
-did you have time to stop along the course for potty breaks and pictures without stressing about the sweepers
Yes, that first year I took pics. I stressed most of the time and still do, just keep watching the time. I only took pics where I thought I could get through quickly. My first marathon, I didn't take any pics and took one potty stop. I was worried the entire time of the sweepers. My pace turned out better than I would have imagined, good weather and excitement kept me steady. This last weekend weather was a factor as well as injury so I took the entire time. (less 2 minutes) No potty stops and only couple of pics
-what would you modify for next time
I've done Goofy 2 years in a row now and had less time to cross train this last time. Let me suggest that cross training is important. That is what I would do differently. I would go back and add in more cross training during the time of building the base.
Good luck with your journey. Stop by the weekly walkers/runners thread. It is truly helpful. Everyone loves to give advice and support. We enjoy the time as we are training for events and share the excitement of upcoming events.