A levels

What a levels do i need if i were to become an accountant and what gcses would i need???

I would not say there is much that you specifically need. Realistically sticking to subjects you enjoy outside of the ones I mention
GCSE:
maths - very needed
economics - if your school offers it then it is good as it helps you understand stuff about money for the wider economy which considering most accountants work for a firm then useful

A-Level:
maths - again needed
economics - if you still enjoy it then do so
3rd option pick something else you like - my advice don't go for any science as they all are over the top for a-level and considering you want to do accounting sciences are pointless wastes of time that lower your grade prospects

extra curricular try and do things over time on Excel such as making little money tracking table for your pocket money or even your family's finances (if they let you) - there is no rush you have time if you still havent done gcse / a-level etc...