Camerapricebuster does a comparison of 120 film prices, see
here. Not sure how accurate it is, though.
Couple of things worth mentioning... if it's an older folder, the top speed might be quite slow (1/500 if you're lucky, sometimes slower than that). So in brighter holiday conditions, a 400 ISO film might be a bit of a trial (although you might get a 1/32 aperture to help). Also, shutter speeds could be dodgy, so any exposure is going to be approximate. So personally, I'd be taking FP4+ (ISO 125) or Delta 100 (or even Kodak TMax 100), all black and white films. You'll more easily get good images from exposures that are a fair bit off optimal, with black and white. Colour negative (C41) film is also quite forgiving (although Ektar 100 a bit less so, AFAIK).
I'd definitely NOT be taking slide (reversal, E6) film like Provia or Velvia until/unless the camera is well proven.
Once you get your film finished, you'll need to get it processed and scanned. There's a nifty price estimator
here. A few of those labs will off a download link for the scans (including AG and Filmdev) which means you can see your scans a couple of days after posting it off.