So if I did want to buy a book in ePub without DRM, knowing the publisher published them (O'Reilly for instance) where would I go, from UK?

If I buy them off Google Play can I download the ePub?

(And no need to tell me about No Starch, yes if what I want is theirs I'm going straight to source, obvs.)

At least it looks like Play Books allows the Digital Edition download, so it might be a bit of an inept style of work.
Okay that might not work because Google Play Books is _broken._ It redirects me to the "How to download books" page when I ask it to download the Digital Editions file.