Flightranger,
I did my PPL at Headcorn and I now fly from Biggin Hill in a group aeroplane.
If you are happy with what you find at S&K and can afford the costs they propose, I don't see any reason to change. Everyone I've spoken to says that S&K is a fine place.
I was very happy with the instruction I received at Headcorn and can recommend instructors if you decide that S&K isn't for you.