Here's three more for you to try in Kent.

Emmetts Garden, Bow Beech Reservoir & Penshurst Place.

Emmetts Garden and Bow Beech Reservoir are close to each other, near Ide Hill, Kent. (Off the A25)

If you just fancy a drive out in the car, then there's a causeway at one end of Bow Beech Reservoir where you can park the car, lean on a fence and look right out across the reservoir - there's usually lots of wildfowl flying in and out to see. Can be very tranquil at dusk when the sun is setting. A real gem when the weather is nice.

Links are:-
http://www.nationaltrust.org.uk/emmetts-garden/

http://www.kentwildlifetrust.org.uk/rese...tor-centre

Penshurst Place is a bit further on from Sevenoaks.

Link is:-
http://www.penshurstplace.com/