RE: Board for my girlfriend
The GO 129 is quite a bit heavier in the "TufSkin" construction, but at 72 cm wide it should make for an easier transition vs the Carve 111/122/133 as the extra width will be good until you get up above 20 knots alot, and at 90 Kg. that may not be as much a problem.
The Solo is OK, NP gear tends to be a bit "pricey".
Have you looked for other brands, or even really good used or demo sails. I'd suggest spending the most on getting lightweight mast and boom as these components can be carried forward fairly easily if you shop for sails that are compatible.
Hope this helps,