You need to get Pete Reads Blue Book. I think you can google for it.
You don't replicate your Sunday run on the turbo as you say - would drive you mad !
If I couldn't get out - I'd do something like warm up, then about 40mins at 80% of MHR, and then some intervals on top of that.
But I'd rather go out. The 40 min session is always a good one and helps build your base, and when you are fit, the intervals are brilliant.