The chemistry needs to go up to a B, or I wouldn't apply to kings unless you have special circumstances.
In terms of your question, knigs are more competitive as they take on less people and don't ask for an interview. Therefore only apply if you think your P.S. is top notch! Also if you miss your grades don't expect them to take you on, they are not lenient in these cases, trust me I know!
On the otherhand LSOP takes on more people, and is definitely much more lenient. From wot I heard someone hear got into LSOP with ABC. As long as you get an interview, expect to get an offer unless you really mess up...
Also you may have to retake that maths if you can, getting it up to a C would be good. Also if you decide you don't wanna include it in your UCAS application, kings will have to give you an interview amnd probably a higher offer eg ABB.
Good luck with your application!