Ian,
If you can't do 100MPW in singles then don't do it at all.
1. You need a weekly long run of 120-150 mins
2. Run AFTER school and be sure to check the weather.
3. Plan your entire life around your running.
4. Your weekdays should consist of something like this:
Wake
Eat a huge breakfast
Go to school
Eat Lunch
Leave School
Have a small meal such as a (organic) peanut butter sandwich.
Start your run by 4:30.
Hot bath/shower immediately after run and post run exercises, stretch and massage your legs at some point during your bath.
Get out put your pajamas on.
Rest until dinner.
Eat dinner.
Rest until bedtime.
Bedtime, you'll need a minimum of 9 hours of quality sleep. Preferably 10-12.
So basically wake at 7am, in bed by 8:30-9:30pm.
Bottomline, if you arent gettin adequate rest each day, you simply WILL NOT be able to maintain 100MPW, you just won't, you'll fail.
I get the feeling you don't respect what 100MPW really is. It's easy to say, but of course doing it is a horse of a different color, lol.
So, a in nutshell, your life can consist only of sleeping, eating, going to school, and running. The rest of your time should be at home on the couch with your feet propped up resting/reading or napping.
100MPW is 100MPW
I mean its 100MPW, there are elite Americans who don't do it. You need to start at 50miles per week. It will take longer than a year for you reach 100MPW so just remember that your are in this for the long haul buddy. As much as you might want it, you won't wake up running 100MPW. If you are going to get to being able to run 100MPW, then running is all that your daily life will consist for 1 year at the absolute mininum, and that is if everything goes right. AND REMEMBER, if you get injured or sick it will slow your climb to 100MPW dramatically. So if you are overtraining you will eventually get injured. So ideally, your main goal should be avoiding injury at all costs. As Daniel Komen said, "HAVE PATIENCE; IT TAKES YEARS OF HARD TRAINING TO GET GOOD RESULTS."
I recommend eating 3tbsp per day of organic extra virgin coconut oil, do the reseach.
Also 3-6 tsp per day of organic raw unfiltered apple cider vinegar to keep your immune system running at 100%, do the reseach.
Good luck.