PENCILS - A non-repro blue pencil is great to use because you don't have to erase it. Anything that saves you time is an asset. Saving time becomes very important when you need every second to meet a deadline.
Now if for some reason you do not want to use a non-repro blue pencil, then you can use a regular gray pencil. Even though pencils are referred to as having lead, it is really mostly graphite. We call it graphite because the man who discovered graphite thought he had found lead. Today, graphite and clay are mixed with water and pressed very tightly together with high temperatures into thin rods. Graphite gets it name from the Greek word meaning "to write".
You really can use any type of pencil to draw. Be aware that soft graphite smears and makes a mess and hard graphite can dig into the paper if you're not careful.
Art pencils use the English scale to grade graphite which is a combination of numbers and letters with "B" standing for soft graphite that gets blacker the softer it is and much messier. The higher the number the softer the graphite and the more it smears.
"H" stand for hardness of the graphite. The higher the number, the harder the graphite and the lighter the pencil mark made.
"F" stands for fine point. As you start from F to 9H the pencil is able to hold a fine point longer.
The American grading system uses numbers. You may have used a number 2 in elementary school as a kid and HB is equivalent to that pencil. So you can keep using it to draw if you wish. But you may want to put your big boy pants on (or big girl panties) and do something bold; EXPERIMENT.
The fun of art is exploring and playing with the tools to see what they can do. Run away from anyone that tells you you should use an HB or 2B pencil. Buy every pencil grade and draw with them all and see what works for you.
When I don't use non-repro blue, I have personally settled on a 2 pencil combination. I use the 4H to do rough drawing, then use a 2B to tighten it up darker. Why? Because the 4H pencil lines I don't have to erase. Once I lay down a darker graphite the 4H lines are barely noticeable.
So what are you waiting for? Go play with pencils!