FTTC = Fibre to the cabinet
Sky... I'd assume that the vast majority of complaints you've seen regarding Sky broadband have been for Sky's non-LLU service called "Connect"? Sky Broadband "Connect" is a re-sold BTWholesale IPStream product, which is subject to traffic management & usage limits and has been widely criticised as being utter crap (doesn't take much searching to find complaints about it). Sky's
LLU services, however, are excellent.