Your vision must be 6/6 (for Goodness' sake, get over this '20/20' thing - that is not used in UK!) in each eye. It is not a combined vision thing, both your eyes must be 6/6 or better.
As I have already said (but some people either can't or won't read), the RAF does not pre-select pilots for a particular aircraft category. All pilots are selected on the basis that they are fit for any and all roles. During training, you are streamed to the role which your ability and aptitude best suits you, and for which vacancies are available. You do not have a choice to which role or aircraft you are sent.You may be asked your preference - but thay won't take any notice of what you say!
planecrazy the RAF are not taking people with 'poor' eyes. Nothing in this thread has suggested they are.
Scroggs