It looks like May 16 is the confirmed retail release date in US, UK, and Europe. I see pre-order listings in all 3 regions, like this:
https://www.bullmoose.com/search?q=u...3006|-3008|-53
https://www.roughtrade.com/search?q=...ion=Pre-Orders
I'm sure they will show up on Amazon soon too, as well as your favorite local record store, or other retailers where you may find discounts, bundle deals, free shipping, etc.