website to learn free grammar and fluent english?
Well, you cannot learn just from the theory, you must practice as well. Now, when you start practising english, you might make mistakes. But only by practising and making you will be able to correct.
For more practise and correction of your mistakes, Grammerly may help. You can also use some paraphasing tools, to get hold of more synonyms or antonyms, to enhance your vocabulary.
I hope this helps you!