Hey Mauser, welcome to the forum and congrats on taking up fly fishing. You've got some great fishing there, and it sounds like you're doing best to take advantage of it, though the trees seem like a challenge- we've all been there
I haven't fished too much down your way, but I'll chime in for what it's worth just to give you some ideas, but take my advice with a grain of salt and defer to local knowledge from folks that have a better handle on the local fishing.
An 8 weight is a great bass (both largemouth smallmouth) and streamer rod for big trout. It will be a little heavy for panfish and “normal” trout fishing with dry flies and nymphs, where a 5 weight would generally be more common. But you can certainly use it for them too if that’s what you’ve got. It just might be more difficult to get a stealthy presentation.
You’ve gotten great advice about getting recommendations from a local fly shop, but it sounds like you’re having a problem finding one.
I’m not sure where you are in TN since I’m a Yankee and don’t get down there too much, but here are some places to check out. If you’re anywhere near Knoxville, there’s www.creelflyfishing.com
In Nashville check out http://cumberlandtransit.com/page.cfm?PageID=58
It has a free upcoming Intro to Fly Fishing Class on Aug 20 and a Fly Casting Class for 10 bucks on Aug 22 (check their upcoming events page) and there is or was Fly South in Nashville (not sure if they’re still in business because their website seems like it down, but you can try giving them a call at (615) 251-6199, and there is/was a flyshop at Caney Fork Outdoors in Silver Point 931-585-2222. There’s also www.timsfliesandlies.com
in Lynchburg (as well as having a shop, and doing guided trips, he offers casting lessons for 20 bucks and hour which might be a good investment if you feel like you need a tuneup and are close to him)
If you can’t find a shop near by, some basics would cover you for now. Flies for trout will vary quite a bit depending on the water type since different food types will be more prevalent in tailwater streams compared to freestone streams like the Tellico-- and since it sounds like you fish a lot of tailwaters, generation schedules will affect the fishing, with high generation = big streamers and periods of low generation where smaller flies like scuds, midges and caddis might be a better choice. Panfish and smallmouth and largemouth bass flies will differ from trout stuff to some extent too. But you can put together some basics that will cover you for a bunch of different situations with some patterns that will do double duty for bass and trout and then build on them with specific recommendations from shops down there.
Here are a few patterns that might be good for your 8 weight, just to get you started:
Black Conehead marabou muddler size 6- The heavy weight of the conehead will help the fly get down in fast water and this one might be a good choice for high flows, heavy generation for big trout, and would be a good small mouth and largemouth fly too.
Black Bead Head Wooly Bugger size 8 and olive size 10. These are good all around patterns for trout and bass. The smaller size 10 olive also doubles for dragon/damsel fly nymph in slower water lakes and ponds.
White Zonker size 6 for high generation below dams when shad get washed over. It’s also a good imitation for them in lakes. A good choice for big trout below dams and bass (including stripers and wipers if you fish for them down there) in lakes.
Grasshopper pattern size 10 good topwater dry fly for trout and bass in summer
Chartreuse Clouser Minnow a great smallmouth fly for moving water
Crayfish imitation another good smallie fly
Gurgler a great topwater smallmouth and largemouth fly in moving water
Bass popper size 4 or 6 great for largemouth late in the day for weedy areas in lakes and ponds or slow moving streams.
Smaller stuff for trout and panfish, generally fished on 4, 5 and 6 weight outfits. These would be good choices for the generally small stuff that hatches in tailwaters like the Cumberland, Clinch and Caney during low flows. This can be tough fishing with small flies, light tippets and very selective/finicky trout. I generally prefer larger flies for panfish in size 10-12 so they don’t swallow them, but these flies will work for them too.
Dries (add a paste type dry fly floatant like DAB or Ghinke)
Tan Elk Hair Caddis size 16
Parachute Adams size 16 and 18
Foam ant and/or beetle size 14 good summer time trout fly, and always a good choice for panfish.
Zebra Midge olive or black size 18 is a good choice for tailwaters when there’s not too much water being released. Fish it as Larry suggested as a “dropper” using a dry fly on top, and tying a short section of tippet to the bend of the dry fly with an improved clinch knot and dangling the midge about 12” below it.
Olive or Gray Scud size 14 below dams during low flows for trout
Bead Head Pheasant Tail Nymph size 18 another good tailwater fly, as well as all around trout pattern.
Green Bead Head Caddis Pupa size 14, a good searching fly for trout in streams
Panfish popper size 10 or 12 great bream fly and fun to fish
You might want to check out Trout Unlimited and the Federation of Fly Fishers to see if there is a local TU chapter or FFF affiliated club near you. It’s a great way to jump start your fly fishing career—lot’s of informative meetings casting clinics, and group trips to local waters, and lot’s of local intel on the local fishing. Here’s some places to do a search:
Good luck, I hope some of this info helps a bit. Keep asking questions, I'm sure folks will do their best to get you going.