I would also recommend doing all of the new spec GCSE past papers (i think its from like 2015). If you dont have time, do the most recent ones. I did my maths GCSE in 2023 and got a grade 9, mostly because i did all the past papers. Make sure once youve done a past paper, go through the questions you lost marks on and revise those topics as they are your weaker areas. Also try and practice every day because maths is all about practice.
Hope this helps!