Thanks Wojtek!
Bili, the grey posted by Wurger may look slightly darker, on a monitor screen, than it should in 'real life'. The actual mix I would say would be around 40% Black, 60% white, possibly 25% black/75% white, depending on the black paint used. The nearest I can think of that you might be able to compare with easily, is the 'Air Defence Grey' of, for example, the old RAF Phantoms, and the Tornado F3's. Think meduim grey primer, as obtained from Halfords for car body repair work, and you're not far out.
Before going to the expense of buying and applying CAA approved (or acceptable) paints, it might be worthwhile visiting a model shop, and buying a tinlet of each colour, as a guide. Most shops should have either Humbrol or Revell enamels,which will give a quick example, without any special preparation. If this is not possible, PM me an address, and I'll paint some onto some card and send the swatch to you, so that you'll have the actual colours to compare.
Terry.