Many plants manufacture chemicals that can repel or even kill insects. This includes Eucalyptus species, such as Cider Gum (E. gunnii).
However, the amount volatilized into the air naturally is rarely enough to do this, assuming there is another greater motivation for the insects to be present in the first place. The situation would be different for herbivorous insects that actually feed on the plant, as they would come into contact with those chemicals to a much greater degree.
For example, in northern Ireland, Eucalyptus will not likely attract any of the beneficial insects you mention, except perhaps generalist nectar feeders, if the trees blooms. However if there are other resource rewards nearby, such as aphids for a Ladybird Beetle or suitable flowers for a pollinator, then it is doubtful that the mere presence of a nearby Eucalyptus would be enough to repel them.
