You will need an Examiner to sign off your English Level 6 BEFORE you send your paperwork into the CAA for issue of a Part FCL licence otherwise they will bounce it. You may already have Level 6, whenever I conduct any type of Skill Test I always sign the native English speakers off as Level 6 and I know many other examiners do the same.
I would however ask your TRE to complete the Level 6 paperwork for you as a belt and braces exercise.