Which tenses do I need to know for my Spanish i/GCSE exam?

For Spanish exams at this level, an A/A* grade requires a solid knowledge of all the indicative tenses so basically, the more you know about the indicative tenses the better. For students expecting or hoping to achieve a high grade, the subjunctive tenses could be used as well to add some flair to your answer and impress the examiners, but don't be overly ambitious, it's better to not use anything fancy than to use it and get it wrong.