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Wow, I pop out for a couple of hours and all these replies!!
I will work through them I promise.
Anyway as far as I can figure, going off what my daughter remembers, is that it will be an OS map and they have to find some kind of footpath or navigable way between two points. The distance is minimal she thinks and there will of course be a leader with them.
As for the grid references, these are they,
NU 17441 00342 to NU 16762 00003.
She had written them down on a scrap of paper so lets hope she hasn't made any mistakes, although she rarely does.