Hi , thanks for the replies.
Basically when I put the cartridge in it's very wobbly, and when I open the door it can drop out if I tilt the camera back. I guess I was looking for a satisfying click that lets me know the film is properly loaded, but judging from the comments, closing the door is what secures it in place?
I guess I'm trying to avoid wasting the first roll if film, but it's the only way I'll find out if it works!
Gav