There are sites with USDA zone markings for Europe, and China, and
Aust/NZ. Amazing...

I looked at this one
http://www.b-and-t-world-seeds.com/European.htm
and find the UK is zone 8 or 9. The southern end would be like the
central coast of California I imagine. But the Channel does make a
difference. Pacific Northwest of US wouldn't be too far off.

bahB