Many thanks for the help below is what worked for me
SELECT *, dbo.tPeriod.PeriodDiscription, dbo.[tTimeTable2012-13].StaffID, dbo.[tTimeTable2012-13].DayID
FROM dbo.tSubject
INNER JOIN dbo.[tTimeTable2012-13] ON dbo.tSubject.SubjectID = dbo.[tTimeTable2012-13].SubjectID
AND (dbo.[tTimeTable2012-13].StaffID = 18) AND (dbo.[tTimeTable2012-13].DayID = 1)
RIGHT OUTER JOIN dbo.tPeriod ON dbo.[tTimeTable2012-13].PeriodID = dbo.tPeriod.PeriodID
JB