Hi! It is better to say: " I'm afraid of all my hard work being to no avail." "To no avail " means "no use or without a positive outcome."

You cannot say that because "avail" is a noun, but you need an adjective or adjective phrase. "Of no avail" or "to no avail" can act as adjective phrases. Alternatively, you can use a more straightforward adjective: "I am afraid of my work being useless."

Nath has given you a perfect response. Some alternative phrases could be: ⭐️I did all that work for nothing. ⭐️That's a whole month down the drain. ⭐️What a(n) (absolute) waste of time. ⭐️What have I got to show for all that work? Nothing!