It can be very useful to be able to make up a cassette with the number of shots you expect to need. If you have a dark area (completely dark) available you don't need a loader and won't have to worry about the last few cm of the film being fogged when you tape the film end to the cassette core, before closing the loader.
As an example, when I was a student I found a strip of wood and knocked some small nails in 163cm apart for a 36-exposure load. I took the wood, film, re-useable cassettes, sticky-tape and scissors in to the loft at night and loaded the film I expected to use during the next week or so.
It was simple to hook the film perforation over one nail, unroll the film from the core (held between my fingers) until I could hook it over the other nail, cut the film at that point, return the bulk roll of film to its packaging, use a precut piece of tape to put one end of the film on the core, reinforce it with a precut second piece of tape, unhook the film at that end, roll up the film on to the core, unhook the second end, wriggle the core into the cassette leaving a few cm sticking out, turn on a torch and then get the tape cut for the next cassette. It sounds like a lot of steps, but it flows very simply once you get started.
I'd suggest cutting off (in the dark of course) 30cm of film to practice with in the daylight, as that will reduce the aggravation trying to get the film through the lip of the tight new cassette for the first time in the dark.
If you want to use a loader, then the film is inside the chamber of the loader (you have to put it in there in the dark of course, so check the path carefully beforehand) and the end is taped to the core in the daylight, before a small cover is closed to enable the rest of the loading in darkness. This means the last 5cm or so at the end of the roll is exposed to light, so you have to be sure not to try and shoot until the camera stops, as the last shot (or two) would be spoiled.
For a European stockist you could try Macodirect or Fotoimpex. Possible films to start might be something from Foma, or perhaps Kentmere. These are decent quality films but will really be noticeably cheaper than pre-loaded cassettes - meaning that you can shoot more
🙂
Edit: Here is some
useful information from Roger Hicks' website, covering a lot of what you will need to know . . .