Here is a picture of a lean-to greenhouse I'm building to protect some of my plants.
Looking good so far! Are you going to vent the extra heat in to the house?
That looks great! Are you doing windows, polycarb?
I thought that I would use the back windows for ventilation and on the top of the south facing wall I'm going to put some hopper windows so hopefully there will be a cross breeze and polycarb panels. The North facing wall in the back will be solid plywood so if I have to I can install an active venting fan in the summer if its too hot. Here is a video of my project.
Here is a link that might be useful: Lean-to video
I use my extra heat fro the lean on to heat my house.
It's great to see someone else designing and building their own greenhouse ... and racing Old Man Winter in the process. What you have shown so far looks great!
If you haven't done it already, figuring rafters in a situation like yours is pretty easy, since the nailer is attached to your house and the south wall is braced and in place. Take the piece of lumber that will become your rafter pattern, and hold it against the end your your nailer and the end of your south wall (not on top, but against the side of these pieces). Mark a plumb line by tracing the face of your nailer at the top of the pattern piece, and a level line along the bottom of the pattern piece by tracing the line of the top plate of the south wall ... now you have your angle and can make a pattern from here. (BTW, I'd cut bird's mouth, if it was mine)
I figured and fiddled with rafters while building a shed years ago. Then, I got this trick from watching some pros figuring rafters on a screen porch they were building at the house next door.