Q8, I fully understand we all have lives to juggle and we have to fit our running in around it..there are usually ways of doing so it just takes some thinking. Can you run to work for instance, run in your lunch break or home from work, double days? Do you have access to a gym at work? , I'm not aiming the questions at you just throwing out thoughts to be considered when planning.
I have never done very high milage, I prefer quality over quantity any day and to my mind when marathon training it is more beneficial to do a decent block of long intervals than shuffle round some dead miles. So I view training for 100k the same, I trained well for 26.2 miles, ran a good race, bagged a pb, recovered for 1 week then ticked over for the next 3 weeks. I started the 100k with a walk/run regime and watched all the keen lot go off into the distance. I carried this off until we got the hills and swapped for a walk the hills jog the rest when mud allowed. By half way all the keen lot were coming back to me or dropping out.
At the moment I am training for a 100 miles, longer but same principles. For any distance event, most of it is mental strength anyway.