Could you check it?
Could you, please, check my sentence or suggest a better way to say it?
Here is the context:
a person asked me if I would have free time in the evenings and now I need to explain that I was wrong and I will not have any time for the lesson in the evenings.

Here is my sentence:

Hello. I'm sorry but as it turned out I won't be available in the evenings after all.

Question

Could you check it?
Could you, please, check my sentence or suggest a better way to say it?
Here is the context:
a person asked me if I would have free time in the evenings and now I need to explain that I was wrong and I will not have any time for the lesson in the evenings.

Here is my sentence:

Hello. I'm sorry but as it turned out I won't be available in the evenings after all.

Answer

"Hello. I'm sorry but as it turned out I won't be available in the evenings after all."

Your sentence is correct.
Some alternatives:
 "Hello. I'm sorry, but I've just realized my evenings aren't free, after all."
"Hi, I apologize, but I've just discovered I'm no longer available in the evenings."
"Hello, sorry for the inconvenience, but my evenings are no longer available."

Не упустите возможность выучить язык, не выходя из дома. Ознакомьтесь с подборкой опытных преподавателей и запишитесь на свой первый урок прямо сейчас!