The Department for Education collects information on absences through the termly school census. The department collects data on the number of possible sessions, number of authorised absences, number of unauthorised absences and the reason for absence for each pupil. The reasons for absence do not include a category which would enable sessions missed due to a lack of access to menstrual products to be identified. Full details of the absence data we collect in the school census can be found in the census guidance here: https://www.gov.uk/guidance/school-census.
The department has sought to establish whether there has been any rigorous national assessment of the prevalence of period poverty or its impact on attendance, however none appears available. We reached out to school stakeholders in July 2017 through the Association of School and College Leaders forum asking for contributions on the issue and have received a very limited response. The department is producing additional analysis of the absence data in order to look for evidence of period poverty and will publish findings in due course.