The number of non-resident parents that are in maintenance arrears through the Child Maintenance Service is published in Table 7: of The Child Maintenance Statistics, available on line at; https://www.gov.uk/government/statistics/child-maintenance-service-aug-2013-to-mar-2018-experimental
The department does hold data on the amount of money which is outstanding in such cases. However this information is not routinely collated at constituency level and could only be provided at a disproportionate cost.
You may also be interested in the Child Maintenance Service Statistics: Regional Tables which are published quarterly at the link above. These tables contain the number of parents using the service and measures of compliance for the Collect and Pay service at local authority level.