Your GCSEs shouldn't be a problem at all - they're good enough to get you an interview, as are your 4As, and after that, you're being assessed on so much more than just your grades. LNAT score, personal statement and interview are just as, if not more, important, so just focus on those now. I've heard of people with worse grades than yours getting through. You can't change your GCSE grades now, and you may as well apply for the unis you want to go to. Your GCSE grades certainly won't rule you out.
(Just to give you an idea, I got 4A*s, 6As and 2Bs at GCSE - I don't think they worried too much about my GCSEs to be honest)