The UNESCO Institute of statistics have release more data via their dedicated Institute of Statistics data website. Select education from the themes on the left of the screen. New indicators are linked to the Sustainable Development Goals and include or the first time, the UIS is releasing SDG indicator 4.5.4, which provides a breakdown of expenditure per student by level of education and source of funding (government and households). See the explanation on the blog.
An interesting site for the UK is the Education Datalab launched in 2015 linked to FFT Education Ltd. It provides quantitative analysis of education policy and programmes conducting analysis on National public data sets and teaching workforce data for the UK. All levels from early childhood to higher education are covered. See the blog for examples of manifesto analysis covered during the election. Official ONS education and childcare datasets