Can i do medicine with a grade 6 in math

Yes - but double check uni requirements, in order to supplement your maths score you need to get a high UCAT or BMAT. Also apply strategically, don't target unis like Oxbridge that care about GCSEs

what if i resit my maths gcse, will that increase my chance, i want to go to kings collage,im not sure if i should resit or not. im hoping to get 2 A* and 2 A's in A levels by end of year 13 do you think kings would be good?

I'm not sure how KCL look at resits for gcse (often universities are less strict with gcse resits that alevel) but they do put the most weight on achieved grades (GCSEs) and UCAT results for pre interview selection. Your gcses may be fine if you have a really high UCAT score with band 1 SJT for kcl but it is often competitive pre-interview. If you are thinking about resitting gcses it may be worth emailing them to see if they look at resits differently. As has been previously said on this thread apply strategically.
This link has the requirements and selection processes for each medical school:
https://www.thestudentroom.co.uk/showthread.php?t=7312527
Hopefully it helps.

Yes - but double check uni requirements, in order to supplement your maths score you need to get a high UCAT or BMAT. Also apply strategically, don't target unis like Oxbridge that care about GCSEs

Neither Oxford nor Cambridge have any GCSE requirements at all.
Unfortunately, you usually cannot compensate for a lower score in one area by getting a higher score in another, unless a med school uses both GCSEs and UCAT in their shortlisting.

OP, a 6 is fine for many med schools, but Kings does score GCSEs so a 6 would be a disadvantage here, without 8 other 8/9s? As said, do not decide where you are going to apply until you have your stats, as Kings also require a high UCAT, and if you do not getone, then an application here would be wasted

so with my GCSEs, really good A-levels, and a high UCAT will i be able to go to Kings?

GCSEs are worth nearly half of the shortlisting points and with <5 8/9s you would get no points for them. Plus they need A*AA at A level. I think you are going to need a UCAT in excess of 3100 B1 to stand any chance, based off the last couple of years, and even then, it is risky unless you have WP flags, which means they increase your 7s to 8/9 for scoring

sorry, but how does the points and shortlisting work for kings?