Thanks in advance!
Germans had a dark grey tunic with lighter grey trousers the actual grey's would depend on where they where made and how long they had been warn at the front I have seen a photo of 8 german tunics all together and all a different shade. I myself use GW, Mechanicus standard grey and fortress grey on mine.
For the Brits I use Vallejo 70.921 English Uniform as a base uniform colour over a light spray matt black primer. I then highlight or dry brush with Miniature paints 87 khaki. For the webbing I use a 50/50 mixture of the same khaki and Miniature paints 62 sand. A slight variation in uniform colour is probably pretty authentic!
For the Germans I use Miniature paints Dark grey 7 highlighted with mid grey 6 and 87 khaki for the helmet cover. You could use mid grey for the trousers highlighted with light grey. I have never tried painting the red unit numbers on the front of the helmet cover but I have met a couple of chaps at wargame shows that have, but I never seen any photographic evidence as yet!