In the IELTS exam, there's no force on the examinee to use any specific English grammar as there are different structures. The most important ones are the same at the academic level. And you must stick to one variant for the whole test, if you mix them, you'll have a lower score. So I suggest you stick to the American English that you already know better.

As long as the teacher knows how to teach and meets your needs, being a mother tongue speaker doesn't matter. The only thing to focus on is if the teacher has correct pronunciation.

The most important is to stay clear of automatic translation.

Hi, Let me give you an example. Imagine we are sitting in a room and deciding to go to the park tomorrow. We need bread, cheese, and a blanket for tomorrow. I ask you: -What will you bring tomorrow? +I will bring bread tomorrow. Five minutes later, I forget what you are going to bring. Now I should ask: - What are you going to bring tomorrow? +I am going to bring bread.

The present perfect is used for life experiences, past actions with a result now, and the duration of action. Experience: 1. I have been to Paris 2. I've tried Italian pasta 3. I've eaten Spanish food Duration: 1. I've attended English lessons for 5 months 2. I've lived in Rome for 5 years Result now of a past action: (with a stomachache) 1. I've eaten too much. (the streets are wet) 2. It has rained. (it's summer now) 3. Summer has begun, and spring has ended Past simple: The action happened at a specific time in the past. 1. I went to Paris in 2020 2. I tried Italian pasta when I came to Rome 3. I ate Spanish food when I was in Spain Duration: 1. I started attending English lessons 5 months ago(in April) 2. I came to Rome in 2018 and the last one: 1. Yesterday the food was delicious, and I ate too much 2. It rained last night 3. Summer began in June and spring ended in June