Narrowing my search - any suggestions for a nice town off the M20?

After listening to all your previous advice, which was oh-so-helpful at getting me to focus, I am thinking I'd like to concentrate on the Southeast.  I'm hoping to do a lot of traveling during our year there, and am thinking it will be more economical if we drive, rather than fly, with our family of 5. 

My kids are hoping for an area with lots of green space (they love forest-like places), and I am hoping for a nice town or village that we can walk or bike into. I have given up on the no car idea, so will be bravely trying left hand driving!

Thankfully, we don't have to worry about commuting into an office, since DH will work from home, so we can be pretty flexible.  Love to hear your ideas.....

I *heart* Brighton. It's on the coast, sunny, it has a pier and beaches and was a favourite getaway of mine when I lived in London.

They have a Family Information Service, which lets you know what is available in the area.
http://www.brighton-hove.gov.uk/index.cfm?request=c1165312

http://www.familyinfobrighton.org.uk/

sevenoaks, and the villages around it aren't far off of the m20, or the m25.  it's a nice city with some very nice suburb villages.