Here are some of the best flowering plants for pollinators in the UK during the month of August:

1. Sedum (Stonecrop): Sedum produces clusters of small, star-shaped flowers in shades of pink, red, and white that are particularly attractive to bees and butterflies. The flowers are a great source of nectar.
2. Crocosmia (Montbretia): Crocosmia produces tall spikes of trumpet-shaped flowers in shades of orange, red, and yellow that are particularly attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
3. Rudbeckia (Black-eyed Susan): Rudbeckia produces bright yellow, daisy-like flowers that are very attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
4. Helenium (Sneezeweed): Helenium produces clusters of daisy-like flowers in shades of yellow, orange, and red that are particularly attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
5. Aster: Asters produce clusters of small, daisy-like flowers in shades of pink, purple, and white that are very attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
6. Salvia (Sage): Salvia produces spikes of tubular flowers in shades of blue, purple, and pink that are particularly attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
7. Dahlia: Dahlias produce large, showy flowers in a wide range of colours that are very attractive to bees and butterflies. The flowers are a great source of nectar and pollen.
8. Hebe: Hebe produces clusters of small, tubular flowers in shades of pink, purple, and white that are very attractive to bees and butterflies. The flowers are a great source of nectar and pollen.

By planting these and other pollinator-friendly plants in your garden, you can help support local populations of bees, butterflies, and other important pollinators throughout the summer months.