(Reuters) - British construction and services company Interserve Plc expects higher-than-expected debt levels this year and said it would launch plans to cut debt in early 2019 as it faces delays on projects and struggles with a weak construction market.The company, which has been under scrutiny along with some of its peers after the high profile collapse of Carillion this year, also said trading was in-line with its expectations in the first nine months of the year.Interserve reiterated its..