I'm struggling to find a definitive answer about this, does the UK spec car come with a limited slip differential, (or EDL or XDS)

XDS+ is standard across the range. It's listed in the S spec under 'Safety & Security' on page 26 of the brochure 

Thanks for the quick response, I obviously did a "man search"

No problem. Wood for the trees and all that  :p

Just remember XDS only works on fast turns, in response to unloading of the inner wheel.

It doesn't operate in response to loss of traction, such as quick launches or on slippery surfaces.

XDS+ is an extension of the standard EDS electronic diff lock for differing traction across the front axle on FWD Superbs. 

 

The last couple of pages in the brochure explain the mass of initialisms that come with the car.