Rotting cucumbers

Generally speaking the plant concentrates on the most productive fruit - it' quite normal, I believe - so far I've had 3 cucumbers off my plant, probably binned about 12 rotting ones, and at the moment it's being terribly ambitious and going for 5 at once.... my advice is wait until the good one is a decent size then cut it, and if you're sure the others are rotting, cut them off too - it will all come right in the end!