The answer is simple - you should ideally work with a flight instructor who is also a language proficiency trainer.
We recommend language proficiency preparation provided by English trainers.
Most applicants failed the ICAO English proficiency exam because they lacked knowledge of English language. The reason is not usually due to the lack of aviation knowledge. Most flight trainers are not able to help you with grammar and pronunciation.
If you're interested in individual training, contact Aero Language.
+421 910 33 33 11