Hey so ya i took the ielts speaking test. I took it like 4 years ago when i was 15. To be honest all i can say is that try to calm down and do your best. If you think youre having a block say smth like "ummmm" to act lik youre thinking and can eventually say the word. However, my speaking test was the lowest grade of them all so my best advice is focus on the rest and hope for the best with speaking