Starting A Levels at the age of 18

Hi, I’m feeling really confused and would appreciate some advice.

I’m currently 16 and I turn 17 on 13 February. Because of GCSE resits, I would be looking to start A-levels in September when I’m 18.

I’ve been told some FE colleges don’t really offer full A-level programmes, so I’m wondering about sixth form colleges instead (not school sixth forms).

My questions are:

Can you start A-levels at a sixth form college if you’re 18 at the start of the course?

If you are under 19 when the course starts, does that mean the A-levels are still funded/free?

Is age usually a problem, or is it more about GCSE entry requirements?

I’d really appreciate hearing from anyone who has done A-levels later or knows how the funding rules work.
Thank you!