Would this give you the correct result?

SELECT

Users.Department as Dept,

CaseTypes.Description as Case_Type,

Users.Code as FE,

COUNT(Matters.FeeEarnerRef) as No_of_Matters,

ISNULL(SUM(Usr_Int1.Estimated_total_fee),0) as Fee_Estimate

FROM

((Users LEFT JOIN Matters ON Users.Code = Matters.FeeEarnerRef and (Matters.Created >= GetDate() - 7 AND Matters.Created <= GetDate())

INNER JOIN CaseTypes ON Matters.CaseTypeRef = CaseTypes.Code)

LEFT --This is the only change

JOIN Usr_Int1 ON (Matters.Number = Usr_Int1.MatterNo) AND (Matters.EntityRef = Usr_Int1.EntityRef))

WHERE

((usertyperef =1) or (usertyperef = 2))

GROUP BY

users.code, usertyperef, users.department, casetypes.description, users.department, casetyperef, users.feeearner

ORDER BY

users.department, casetyperef, users.code;