Several issues in this thread, so I'll try to cover them, starting at the beginning.
While a sheet of glass may be less expensive, it is not easy to deal with. You have to move it (and probably the light) every time you feed the fish. $45 just for the cover glass is a bit expensive. You can get an entire hood with a fluorescent fixture for less than $60 for a 20g long. As you're in Canada, take a look at this online supplier, I use this one a lot: Search - Pets & Ponds
The cost of the entire hood is worth it, but if you want different lighting then a glass cover with a hinged front pane and the light would be better.
You can do a single T8 fluorescent tube (tube length preferably 30-inch, or 24-inch) with a good tube like the Life-Glo. Or an incandescent hood with 3 sockets, using Daylight 6500K CFL bulbs. Or perhaps an LED like the Bright Marineland.
Fertilizers. Some plant nutrients are only taken up via the leaves by all plants, so these need to be in the water column. And floating plants obviously need water nutrients entirely, and with your proposed fish floating plants are essential in point of fact. Substrate tabs do not release into the water (according to the manufacturers). The first fertilizer to use, always, is a good complete liquid; Seachem's Flourish Comprehensive or Brightwell Aquatics' FlorinMulti are two I use/recommend. Heavy feeding plants rooted in the substrate will benefit then from substrate tabs in addition to the liquid. Sanguinefox's suggestion to break some apart and lay it under the sand is good; this will kick-start.
I would avoid Wisteria in this small a tank. Crypts, pygmy chain sword or chain sword would be ideal in the substrate. If you have medium hard or harder water, Vallisneria is another, but this does not usually do well in soft water, and it needs a bit more light than the others mentioned. Stem plants tend to grow very fast so I would avoid them, except perhaps for Brazilian Pennywort which can be left floating for a nice cover, avoiding the issues with Water Sprite. Though I use WS in all my tanks, even my 10g and 20g, and just pull off the daughter plants and discard the parent plant periodically during the water change to keep it in check.
You need to ascertain your GH of the tap water. This is more important than pH. Also the KH/Alkalinity which will tell you to what extent the pH might shift. I have an article in the Freshwater Articles section on the relationship between these if you want some background.
Plants can be shipped, I have sent plants to some members in Canada and they have always made it [only send during warmer weather]. PM me if interested. There are also Canadian online suppliers.