First, welcome to the world of ball pythons!
What do you mean by Jungle Morph?

There are jungle pastels, but I wouldn't be too sure what you are getting here. I recommend buying from a breeder so you don't get any presents along with the animal (like mites or parasites or an RI). A 20L should be fine, but if the snake doesn't have tight hides (no logs) and is a baby, it may need to be switched to an even smaller enclosure.

For a 20L tank you probably would only need one UTH, unless your home is very cold and you need them both for the ambient temperatures. You'll also need a thermostat to control it's temperatures, or they will get too hot on their own. Also, I recommend taping the UTH to the underside of the enclosures instead of using the actual adhesive, so you can move it to another tank if you need to.
You will also need some thermometers to monitor the temps inside the enclosure. Digital ones with probes are best.
Aspen bedding is good. I personally don't recommend the carpet because it harbors bacteria. Paper towels and newspaper are also very good substrates.

Good luck!