Ahh I have to apologize, I just checked the KFC website apparently in the UK we do have mashed potato. I've just not noticed
. or its not at the one i go to
according to KFC UK website you can get as sides:
Fries, gravy, baked beans,coleslaw, corn on the cob, creamy mash potato, garden salad, southern rice.
I must admit I've never seen the southern rice or potato so it's maybe not in all outlets?