Hey Jonathan, and welcome to the wonderful world of aquatic gardening!
40W will be quite low for a 29gal (tall) but you could never the less grow some things in it low tech, meaning w/o co2 and ferts. Water changes should provide some of the trace elements for the plants, and NO3 should come natural. If your plants do start turning yellow and look beat up, you might have to figure out what they're lacking and dose it, depending on your water supply/setup. Low tech is really a trial and error, since you don't want to dose anything without knowing for sure the plants will use it (otherwise algae will!).
I would suggest annubias and swords for a low light tank. Cabomba should do pretty well, and maybe even a wisteria. Java fern is also an excellent choice for a low light tank.
With that little light plants wont really need much co2. So unless you start getting over 60W don't even bother with it.
Look over the low tech section and you might find some of the common questions/problems there too. Post if you're confused about anything. GOOD LUCK and happy gardening!