M: Flex Day (30min to LongRunLength+1mile)
T: Easy + a few fun sprints
W: Easy 30 min
R: Easy including *Run Like A Gazelle*
F: 30 min
S: Long Run (start at 7 miles)
S: Rest
1st Week's Mileage: ~20-25 miles
A few things I'll comment on:
One is the "Flex Day." I feel it is important to have one day a week that you really let yourself go depending on how you are feeling. Say you have just found a magnificent path through the woods or a sidetrack through an alleyway - you don't want to have to cut your run short because of a prescribed time. This is your Free Day, where you can have fun finding a new route and exploring. The only caveat is that even though you can go as long as you want depending upon how you feel, this should never be longer than your weekly long run + 1 mile.
Another is a day that you "Run Like A Gazelle." (The idea is inspired from Frank Horwill.) Meaning run at a brisk, breakneck, easy pace. Breakneck because the thought is that a lion is chasing you. You are acting out your flight response. Easy, because your thought is never on tiring; it is simply on running as effortlessly and quickly as you possibly can. Quick quick QUICK! It should always be exhilarating, first and foremost. If you start to seriously tire beyond being excited-tire, stop.
I really would not recommend speedwork at this point if you had no real preferences, but if you really love doing it, by all means go for it - you seem like an intelligent guy. I know you'll be smart about it.
Tuesday sprints are after the workout and with full recovery. Quick and easy enough to get you excited, speedy and short enough to work on your pure kicks.
Although I think running 7 days a week is good in theory, I think making yourself take a rest day every week keeps you from getting too nutty and pushing yourself too much, as a beginner.
To expand mileage, just gradually add minutes on to your easy runs, and tack on a mile to your long run every couple weeks.
Time, in my opinion, is better to follow than miles for all your easy days. This keeps you focused on building up time on your legs, rather than specific mileage outputs. The long run I like thinking about in miles, however, because it is your weekly reward: it is fun to see your progression in how far you are able to run each week.
Cheers
P.