I'm currently with WJEC for my French GCSE
(Can't imagine it would be drastically different, but)
My french teachers always said, if you wanted to be in the 5% of A*s you'll have to be excellent at everything and can't afford any mistakes
(and that high mark As are similar)
Example,
I recently did my mocks in December,
to get my overall grade, my teacher combined everything (as if it were the real thing)
I had a B overall
Currently with WJEC, there's four controlled assessments and two exams
Controlled assessments contains 2 writings and 2 speakings.
Whilst, the exams are a listening and reading.
My grades were
CA Speaking - B
CA Writing - A*
Exam reading - A
Exam listening - E
Overall - B
So see and try if you can re-sit any of your controlled assessments if you want to be at the very top, because higher tier listening exams are horrible
I'm sure you'll do great
Good luck with your GCSEs
(Oh and be hopeful, UMS marks can be wonderful just as much as they can be confusing
My UMS marks in other subjects last year boosted my overall grades, so keep faith)