Butterflies will stop to feed in your garden if you provide some nectar-rich flowers.
Butterflies fly on sunny days and they like plants in sunny, sheltered spots. They prefer some flowers more than others. There are many published lists and I've experimented with various plants and watched carefully for some years.
Here's my A-Z list of butterfly-attracting plants based upon my own observations and supported with my photographic evidence.
Many of these plants have been successful for me in my garden in Cirencester or in my previous garden 12 miles south of here in North Wiltshire. I live in the Cotswolds, an area of outstanding natural beauty with miles of dry-stone walls, limestone grassland and sheep. Cirencester is a small market town. My home is a modern suburban house with a garden measured in feet not acres.
Although these plants were successful for me, they may not thrive in other parts of the British Isles, particularly where the soil is acidic. I am also lucky to live in Gloucestershire, a county which has recorded 45 of the 58 British butterfly species. If you live in the southernmost counties (Cornwall, Devon, Dorset...Kent), then you have a good chance of seeing many species locally. However, you may not be so fortunate, particularly if you live much further north.
I hope these plants attract butterflies for you too but if they don't, then just remember that it's fun trying and your garden may just have been a little prettier and friendlier for other wildlife too. Read my article on designing a butterfly garden for some more information.
Oh, and if it isn't obvious, a butterfly gardener must garden organically and avoid pesticides & other chemicals.
Look out for butterflies when visiting other gardens, nurseries & plant centres - the butterflies will show you which plants they prefer! The image at the top of this page was taken at the International Festival of Gardens held at Westonbirt Aboretum for example.