I'm starting King's this month too, and I feel the exact same way you do. I've been reading loads on tsr about how people don't rate it but that's probably not a good way to form an opinion on a uni, especially since loads of the people on tsr haven't even gone to uni yet, but I still feel uncertain. Also has to do with the fact that my friend who goes to UCL keeps *****ing on KCL so yeah.
Honestly, I think for me (and maybe you too) it's a case of the Groucho Marx/ Annie Hall thing of "I don't want to be a part of any club that would accept me as a member"- once you get in, it's seems suddenly devalued because it's more human and less of a dream.
All in all, it's a great uni but I understand your reservations as I'm having them too, it's a bit annoying to constantly read that the uni you're going to isn't that good. Also if anyone wants to please reassure me that would be much appreciated! haha