Hiya. I’m a 2nd year undergrad mature student on the HSPS Politics & Sociology tripos. I applied with predictions of A*AA (i ended up getting A*A*A*) & my gcses were way worse than yours! Literally: 3334446A89. Granted, I took mine years ago & I passed English + Maths but the great thing about oxbridge is that due to the holistic nature of the applications (PS, grades, admissions tests, interviews, lnat/ ucat if applicable) it gives the colleges and tutors a better understanding if you would thrive on the course. Also, Cambridge does not about GCSEs as much as Oxford.
There are also younger people in my cohort who have lower GCSEs but then improved in their A Levels/ IBs. Just make sure you do a lot of reading outside of your course, any sort of experience that you can put into your PS & making sure you stay critical. It’s about what you know, yes, but more so how you respond and engage with new information. Knowledge can be taught but the way that you think cannot, it can only be developed through independent study etc. I hope that makes sense aha.
You definitely have a chance. It’s one of your five choices, definitely go for it so you don’t have any ‘what if’ moments in the future😊