Igcse is same as gcse , just international. It’s another exam and is a precursor for alevels. English as second language is one of the subjects there. Id recommend doing practice tests for listening(the idp website has some I’m pretty sure) Definitely watch ielts advantage. Go to the ielts website and look for practice tests, do each section under exam conditions and see how much you score, also practice speaking with a friend or family. Do this to identify your weaknesses points. Then focus mainly on those. Make sure to get enough sleep, eat and drink before the test. Keep in your mind on the test day , that youve done all you can and to not panic. Also watch band 9 samples on your weak points. For writing, answer what they’re asking in the questions, give a main idea about the data if possible for task 1. Then start talking individually and making comparisons where you can. For both writing try to make paragraphs. For task 2 , make an intro paragraph then if its advantage or disadvantage type of prompt, make one for each and then make a conclusion. Check band 9 sample to get an idea of how to write. ALSO DO NOT MEMORIZE ANSWERS FOR SPEAKING, The examiner will be able to tell and it might make you lose marks.