Hasta La Motion!

I’m really new to Nuke, and fairly new to compositing.

I have a challenge I’m trying to overcome where I have a set that looks like a basement window. Outside the window we put bluescreen material. I’m trying Primatte as the keyer. Starting out though the way it was shot and put together, the key has a ton of grey noise in the shot. It’s supposed to be a dusty basement window so I have that as a hedge, but I’d like to perfect it the best I can.

What’s the common way to approach really noisy keys? Should I first try and color contrast the read before even keying the shot? Or is there a better approach?

Any feedback appreciated.