I think 4 runs a week plus your cycle commute may be a bit much. You need to recover or you'll slowly wear yourself out. From what you have said (not running much more than 10k) then I think endurance is the primary concern and speed should be secondary.
My method of doing:
1 interval run (30 minutes 1min fast as you can, 1 min walk)
1 mid distance (for you around 10km at as comfortable pace)
1 long distance (perhaps 15km at any pace that gets you the distance) then increase the distance by a km a week?
I think 4 runs a week plus your cycle commute may be a bit much. You need to recover or you'll slowly wear yourself out. From what you have said (not running much more than 10k) then I think endurance is the primary concern and speed should be secondary.
My method of doing:
1 interval run (30 minutes 1min fast as you can, 1 min walk)
1 mid distance (for you around 10km at as comfortable pace)
1 long distance (perhaps 15km at any pace that gets you the distance) then increase the distance by a km a week?