Hi Lizzie,
If the plants are still fairly small, they "think" they are too young and not ready to reproduce yet. This happened to my plants a couple of years ago, but eventually they started to produce good cucumbers when they finally got going. Also, they may not have been fertilised, and would be
automatically be shed by the plant. All this is assuming that you are keeping them watered, because stress through insuffient water could be another cause. I am sure they will buck their ideas up soon.
Regards, Lyn
Failing that, when they reach 'true leaf stage', if you still can't tell the difference, find someone with both a Courgette and a Cucumber plant, cut a leaf off each and compare with yours.
YO LIZZIE !
My cucumber plants (Telegraph Improved, open pollinated) have sort of done the same.
The embryonic fruits that first developed 'never came to anything', and it's only about 12" above compost level that they've now started to swell into proper cucumbers, and I reckon it's to do with the pollination. I'm removing male flowers, as seen, to stop cross-poll and bitter female fruits, but I'm pretty certain that it's similar to all our problems last year with courgettes. Remember ?
Lol
Wellie