Despite his long publishing history, only one of Ray Bradbury's titles has ever been released through Penguin, the distinguished British paperback imprint. That one title is The Day It Rained Forever, which is a variant of the US book A Medicine for Melancholy.
This is one of many Penguin SF titles documented in a new website devoted to the art of Penguin SF, put together by James Pardey. It looks an excellent resource, and I have already spent a few hours rambling through the contents.
The Day It Rained Forever is covered here - but don't limit yourself to just this one book!