Mvt type 28 shades of olive drab, pick one, type discussion.
For early war British green, cobbatobs light early war British green is right colour, for brown it's model shop leather brown number 64, for late war darker greens it's pick one you like, even the ones that look slightly blue.
Original finish varied, some of the 40/41 colours were garish and non military looking but they used what green paint they had.

Most nos parts are late standardised or refinished, as well you know.