Neil
I think leg colour is not the best way to seperate these two species - both have greenish legs, although wood tends to have slightly yellower and paler legs.
It is better to focus on plumage - green is darker and plainer above with more contrast to the white underparts (very noticeable on the breast) and a shorter supercilium, mostly in front of the eye.
Wood is paler, browner, and more marked above with a long supercilium in front and behind the eye (as on this bird).
They are also rather different in structure - green in stockier.
In flight, the dark underwing of green is very obvious, and the flight calls are different.
