I have no clue what I want to do as a degree,at all I based my A levels randomly to (lol)
1. See what degree courses are open to you based on your A levels.
2. See what careers interest you and then see what degree you might need to get there.
Have a read of these.
Careers- See if you can get any of these books at the careers library or they will have similar for you to read. Try and get ones aimed at your age group. If you cant find then just get second hand from Amazon. That would give you a full approach to helping you decide on a career that might suit you.
Which A levels?