In the end i went with a Vallejo green/blue/grey.
It was with some trepidation i put the decals on - the instructions would have you gloss everything, dip them in water for 5 seconds only, leave for 20 seconds before putting on.
It also advises caution if using a decal softner as they were untried.
Figured i'd have to use some though to get the girlie to go with the change in hull shapes. So put on a layer of Humbrol Decal Set before putting her down.
And it worked a treat.