The Diverite reels are very popular here and in the US. You might find more line than what you need. I still managed to bust the spool in cold weather, some years ago. Then I machined my own Teflon spools - they are indestructible (works for me).
Diverite also carries small spools and I know that they are used to find lost main lines in caves. I know some one that keeps loosing these spools down in Florida. They are small and they come with a double-ended clip. Who knows may be they would work for you?
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I fancy Terry's idea too. It's cheap and idiot proof.
Good luck
Lawrence