Leaving school aged 16 and commencing work is not a barrier to a flying career.
I know a few successful, intelligent Captains who left school
without A levels.
Family / personal circumstances can often be the reason
for this course of action.
There are at least two ways to demonstrate that the grey matter
is ‘alive & well’.
1. Choose an Open University course which appeals to you and achieve.
Given the C-19 implosion there is no need to rush....?
2. The other way to demonstrate your potential is to achieve particularly high marks in the written exams.
All first time passes with no paper less than 90%.
A really high mark in the Navigation can be an indication that
your brain is wired up well for aviation.
Fewest facts, but one where understanding the logic is necessary.