Hard pen and brush calligraphy are almost the same in pen method, stroke order, strength and shelf structure.
Calligraphy and writing are different concepts. The former shows "personality", and it doesn't matter if most people don't know; The latter is for communication and the purpose is to make most people recognize it.
You probably want to calm down and practice writing to improve yourself.
Then you'd better write "block letters" first. This is better than "block letters". Because regular script is the last thing that can't hide failure. It is often said that "regular script is not hidden", which is a bit unpleasant, and others can see it at a glance.
I suggest you learn Song Huizong's fine gold calligraphy first. Ouyang calligraphy, (Mao Zedong colleague) Shu Tong (calligraphy style). This can also be practiced with a hard pen (pencil, ballpoint pen). It's just a different way to hold the pen.
If you insist on learning China's calligraphy, it is Yan Ti or Li Shu. Lishu is the best to master: horizontal and vertical, and the long horizontal pen is always a silkworm head and a phoenix tail. A little bent; I don't emphasize "twists and turns" very much. As shown in the figure. "Han Li" will see some basic skills.
You don't need to buy any copybooks, you can take screenshots from the internet or print one, which is enough for you to practice for a while.