If you're serious and actually put the effort in then it's doable. Prioritise learning core themes and areas you think you could learn in time. I hate revision timetables personally but if you can make one (don't forget to include downtime too) and actually stick to it then that will help.
Take advantage of any support teachers offer or any revision sessions available. Make notes or flashcards, watch YouTube tutorials, pretend to teach it to your dog.... However you learn best. Most importantly, past papers and just straight up learn the markscheme! GCSE has the advantage of you don't necessarily need to even know the content that well, as long as you know the Markscheme and what answers they want.