Maths GCSE RESULTS

Quick question: i achieved an A and a B today in my early entry maths results and have gotten the chance to resit but i wont be able to sit the GCSE further maths paper
would it be better to resit and attempt to get better maths results or stay in my set and hopefully get a distinction in further maths?
tldr: how important is further maths and does it average out a B

Your Maths GCSE grade is far more important. Also time you can spend on other GCSEs.