A couple of things spring to mind.
There is space above the window for a small shelf, even allowing for the slope of the roof. It does not have to be deep, as even a 6" shelf will safely support a 9" box, and you can tip it as it comes out to avoid the ceiling.
Benches you could consider. There are lots of plans for fold down benches attached to the wall that would only steal 2" from your floor area. Perhaps not for the main bench, but for auxiliary benches it is an option. There are loads of free plans online. A variation would be a bench that folds up flat against the glass to stop nosey people casually looking into the shop.
I assume you will be making your own benches. I always recommend in a small shop that everything is on wheels. I have a very heavy bench on 3" locking wheels that is great for cabinet making. It is only 2 foot deep, but if I need extra depth I can pull it out from the wall and lock the wheels.
You could also consider making benches on wheels under the window that are short enough to be rotated and place against the end wall. This would give you flexibility, and making cleaning up a doddle. The only thing to consider is if you were going to have a wall cabinet, on the end, it needs to be above bench height.
Depending on your headroom, you could also raise the floor to give you underfloor storage for infrequently used items.
The ceiling is also an ideal storage space for pipes and long timbers, but you have probably already thought of that.
For the windows, you can buy the opaque window films that will stop people looking in, but do not reduce light. The stuff I got is plastic, you spay a little water on to the glass and just roll on films and smooth it wish a squeegee, you can also re-position it if not straight. Mine has been on for maybe 5 years now, and is just peeling away a tiny bit at the corners.