Retaking A levels UCAS help

Hi, so I have currently done three A levels last year, English and History and got a B in both and I got a D in Maths; I am hoping to retake the Maths A level externally next year. I am a little curious however as to how I would apply to my uni of choice on UCAS before I’ve done the retake? I need to get an A in maths for my chosen course but I obviously need to apply to my selected unis before I resit and I can’t see how I would even be considered with the grade I eventually got. Essentially what I’m asking is how would I apply to universities before I get my grade from the resit?

You list the maths A level on your education section twice. Once in 2020 with the D grade and once in 2022 with a pending grade.

Your referee will be asked to provide a predicted grade for the pending result.

Is it likely my university of choice would even consider me with that grade however? Also how would the referee go about giving me a predicted grade? It’s just if the uni knew the context of the past two years my grade would be understandable