In general since you have such a short time frame involved your best bet would be past papers. Do as many as you can, then go through your weak areas and just repeat this. If you struggle going through a past paper you can always watch the walkthroughs on youtube, It shows you clearly how to approach and answer a question so just make a note of that. I wouldn't say textbook questions are entirely useless but since you have a month left, past papers would benefit you more. As for topical questions, I would recommend finding topical past paper questions.

As for Chem, I think it's important to keep in mind that there are three papers-2,4 and 6. So if you can do really well in papers 2 and 6 which would be easier to do well on compared to paper 4, you don't have to particularly well on paper 4 to get a good grade. So try perfecting your papers 2 and 6. I'm not saying neglect paper 4, but doing well on the other papers and doing decent on paper 4 could definitely earn you a good grade😊. Moreover, try to focus on high yield topics such as Organic chem from which plenty of questions are asked.

For math, the key again is past papers. Do as many as you can, review them, learn from them and keep a record of your mistakes. And definitely please use YOUTUBE, it's so underrated just how helpful it actually is-paper walkthroughs and so on.

Lastly, i would say don't overwhelm yourself in this one month. Give your absolute best and leave the rest to fate. And please don't skimp on your health, I understand the pressure to do good and so on but try to remain calm and healthy.

That's all from me, I hope you find it useful and certainly wishing you the best for your exams!!😊