heh, the britsh aircraft paint schemes are by no means standard...
The most common paint scheme for aircraft (jets and the sort) are either:
All over ADV Grey, or
ADV Grey and Olive Drab (a greeny colour) mix...
For Helicopters it is either:
All over Olive Drab (as seen on all the Chinooks), or
ADV Grey and Olive drab mix...
And mixed in amongst these are special schemes for celibrations, and then theatre special schemes, such as a fetching all over pink, or ADV Grey/Pink mix... lovely
The reason you won't have seen any ADV/Olive Chinooks, is because there aren't any... simple as that...