I was also going to suggest Perfect Fit, they were the only blinds that I could find when I was looking a while ago. I haven't got them yet myself as i'm not sure if they are a good idea if you suffer from condensation on the bottom of your glass during the winter. Don't want moldy blinds.
Perfect Fit are great, especially venetians. They look quite classy even though they are not particularly expensive. They look like they are part of the door/window. They wouldn't help with insulation though. I think you can probably get Perfect Fit roller blinds with a blackout/thermal fabric.