Between the ages of 16 and 19, if the child is enrolled full-time in school (more than 12 hours per week and the course is up to and including A level), child maintenance for the child must be paid. This does not apply to advanced study, like study at a college or university, this only includes non-advanced study. Although a child may have several long breaks, the non-custodial parent still owes child maintenance during school breaks. If the child leaves full-time schooling in the summer, the non-custodial parent generally owes child support until the first week of September, of that year.
http://www.sfla.co.uk/endmaintenance.htm