If i'm being completely honest it would be extremely hard to get in, as whilst they say that the requirements are only 6 in english and maths, KCL weight GCSE's extremely highly compared to other unis. They score the highest 8 GCSE grades an individual has and most people who get in have all 8 of these being 9's and 8's. The chances of getting in with not all 8's/9's or even just 99899977 would be slim as most people who apply will have the top 8 grades being 9's and 8's and therefore would be provided the interview over say someone with one 7 and the rest 9's. As you've received a 5 in english lang they would immediately reject you as you haven't met their minimum entry requirements so if you still want to apply you would need to resit.