Help With A-Levels :D

At the moment i am currently in year 12 taking media studies, public services GCSE and travel and tourism. I hate the subjects i have chosen and i have always wanted to progress into aerospace engineering at university.

I have applied for lots of 6th forms to resit year 12 offering courses i want to take and also applied for my own

For example at John Leggot i have requested to study

Chemistry
Economics
Computer Science
Electronics

But i really need my maths and physics to progress onto the course but also really want to study these subjects to

I have opted to study maths and physics at home study and pay the required price of £400 to study them both at home with A-Level qualification so i can get on my required course

Is this too many A-Levels to be learning at once ??

I work saturday and sunday at sainsbury's

For my university degree for the bach they are wanting BBC at A-Level including maths and that is to study aerospace engineering with a year abroad

What do you guys think really

Doing 6 A-Levels improve my chances or just weaken them ?
I have time to study but will it still wreck my chances ??
What do you guys suggest

Also i cannot take maths and physics at my 6th form college so them two are having to be done in private study