Are the lights T5 HO 10K/460nm? Is that a 40gallon tank?
Researching your plants I found that the Blyx japapo is the main plaint that you will need to keep an eye on. It needs high light and co2. Perhaps you can use flourish excel instead of co2.
Whether you need ferts depends on the plants reaction to your light and the minerals in your water column. The substrate will also provide some nutrients. What is the substrate?
Some dose on a regiment and do weekly water changes.
I lean toward the minimum, thus once the tank is establish water changes only have to be done monthly. The blyx will probably need some potassium nitrate.
Dry ferts can be bought cheap on line at http://www.rexgrigg.com/
. Rex is cheaper but delivery slower than the other.
For potassium nitrate I am using Specracide stump remover from Lowe's. Something suggested at 1 of the aquarium forums I visit.