I would say that it is hard to find a high-quality sketchbook from mass production. A sketchbook is a thing intended for amateur in the first place, the paper that is used for production does not have obvious advantages.
However, if you have access to art stores, you can find something suitable.
I would advise you to look towards professional materials, some "drawing folders" can be held together with glue or a spiral.
If the girl paints with paints, look for thick paper with fine/medium grain. If she draws with pencils, drawing paper is suitable - it is not expensive, and is often produced in the form of a "sketchbook".
Regardless of the material, try to look for paper with a density of 180 g/m - no less. If you need to draw with markers you need paper over density 240 g/m.
Artists who make hand-made sketchbooks, are quite a few of them, and they specialize in a specific material. I can't tell you the site, but I think Etsy or a few FA users can help, a group of artists on a social network maybe too.
You have two months, so I think it's better to find an artist/crafter from your country, because postal services may not be able to international shipping on time.