I sympathise about the Cabbage Whites. We have small birds in squadrons (Mr. J2 feeds assiduously) so I felt OK last year and thought that the birds would eat the caterpillars. Don't fall for the 'balance of nature' stuff. They didn't, I lost all my brassicas and then someone told me that they don't like them. Back to picking them off manually. :(
Otherwise, we're short of garden butterflies too. Late, cold spring has hurt them, but we are now seeing them in the lanes and hedgerows, so keep hoping. The bees adore the lavender bushes I planted, and the herb bed is alive with them too.