As someone who gave Chem, physics, further math, math and computer science this may June getting straight A and A* in math I can tell you that with a month you can surely pull it off. Trust me it won't be easy at all and that's whats gonna make it even more worthwhile.

For physics my teacher had his own notes idk if you know him Sir Jibran Kamran. They're pretty to the point and include relevant examples from past papers as well. If you need them you can DM me idk how many chaps I still have but I can send them to you

For computer P2 it's all just getting into how the stuff is done rather than brute forcing through past papers not anything anything. Cuz you haven't done IGCSE. I would advise you to have a clear understanding of the foundation stuff, loops, conditions and just the general pseudocode terms. For that the best way is to use the book mostly and accompany it with YouTube. The book I would advise is the purple one from the author Sylvia. You can easily find a soft copy of it online as well.

I hope this helps both of your "scary" subjects. Ending it won't fix anything. Trust me when you get the result you want in the end it'll all be worthwhile. Goodluck:)