Hey,
12 GCSEs is fantastic, usually most be people do 10 or less. Obviously, like you say you need to continue on to do further eduction, but you've given yourself a fantastic start. I'm, fingers crossed, going to get 11 or 12 GCSEs and hope to be a lawyer too. I can't see any college or sixth form turning you down with those grades. You might want to look into what universities you might like to go to, and see what A levels they want for a Law degree, and this should help you select what A levels to do.
Well done, and good luck for results day =)
xx