I lived in Bellingham for a year and messed around alot on the Nooksack. It seems to be a tough river to fish. I was there in the winter and early summer when the water was high.
I would assume staying near the hatchery would be a good bet.
One area I visited alot was the area where the middle fork branches off. Turn off of Mt Baker highway onto Mosquito Lake road. Park at the bridge and walk down river. There are a couple deep spots there at the bridge. You can also continue downriver on the Middle fork. I walked it many times. I never caught a steelie in there. I was just a beginner trying to figure things out.
There is also a road 1st left after the bridge ( cant remember name ) you can follow that road along the river. I bet there are some good spots there.
Also the hatchery itself has a trail that goes behind the holding tanks. It leads to the little creek that the hatchery fish come up. You can cast from where the creek runs innto the main stem.
Don't get frustrated. Talk to people, and ask questions. Timing also helps. After a good rain, when the river starts to clear is a great time.
I am unsure of there summer return, but I know from experience their winter steelhead run is't anything to write home about. ( I volunteered at the hatchery for a couple weeks). Salmon returns seem to be good. (Sept And oct)
I never realized how close another great river is. The Vedder. I never fished it but I have heard its a good one. probably 1.5+ hours from Bellingham.( in canada )
Also the cascade river that branches off the skagit is a good one! 1hr or so away
Beginning is very frustrating but when you finally do get a steelie on the hook it will make up for all those zero trips!!!
Good luck! and relax ( take care of that heart!)
Bill Herzog's drift fishing for steelhead is a great beginning book
Remember you want to feel that tap tap tap on the bottom while your drifting!