Update. Managed to get the 23rds closing stock with this
SELECT f1.Year, f1.Week, f1.Date, f1.[Combined Dept], (SELECT TOP 1 f2.ClosingStock FROM qryRollingForecastWorking f2 WHERE f2.Date = (f1.Date-1) and f2.[Combined Dept] = f1.[Combined Dept]) AS OpeningStock, f1.Arrivals, f1.Orders...