I think I only fished Yewtree once... might be wrong about that.
Three places in Kent really stand out in my memory.
Woodchurch, Ian the owner is a lovely bloke and the fishing is superb. IIRC he does sporting C&R tickets as well as catch and kill.
Stowting, again the owners are lovely and the water clarity is beyond belief for such a small, springfed water. C&R only really, unless you want to pay by the lB.
Tenterden Trout Waters - Barry's approach to fishery management was, when I first visited, unique. You can catch up to 10 fish and you may keep the best of those afforded you by your ticket. If you bought a 4 fish ticket you could catch 10 and keep 4, 2 fish ticket meant catch 10 and keep 2 - etc. Water clarity always was a problem as it's spring fed and suffers badly after rain due to run off. There's a few carp in the lower lake if you really fancy a challenge, the top pool is a little like fishing in someone's garden pond due to the goldfish.
If I were to take someone anywhere in Kent it would be one of those 3. Woodchurch can be difficult, but the top of the water fishing when it's on form is simply fabulous. Stowting if you want a lovely setting, great fish and challenging fishing for a smallwater. Tenterden is probably the best suited for newcomers - have a look here:
http://www.tenterden-trout-waters.co.uk/
Cheers,