Simon, if you're talking about this scheme...
http://www.airliners.net/open.file?id=1277028&size=L&width=1200&height=812&sok=&photo_nr=
..then I can at least ID those colors. First, about that blue patch on the bottom of the fuselage. It seems to be the same color as the blue on this USAF C-32...
http://www.airliners.net/open.file?id=1284215&size=L
...and my C-32 kit instructions identify it as Testors 1108. Eyeballing my bottle of 1108, I'm thinking they have it right, but I think this Bright Blue gloss spray...
http://www.squadron.com/ItemDetails.asp?item=TS1210
would match it, too. When you decide what to use, please let me know, because I want to get that shade exactly right on my C-32.
As for the color on the cowlings, looks to me like Testors 2033 Blue...
http://www.squadron.com/ItemDetails.asp?item=TS2033
...or 2130 Flanker Blue...
http://www.squadron.com/ItemDetails.asp?item=TS2130
...is going to be what you need.
I'll add your A319 to the front page...looks like it's going to be a lovely bird, and good job on those flaps!
ON EDIT: Simon, be careful following my paint advice...I just checked around some more and it loooks like bot the paints I recommended aredarker than the cowling color. It looks like the color is very close to FS 35466, but I'm not finding any paints that match that FS number exactly. Looks like the only way to be sure will be at the hobby store eyeballing the actual bottles.