Try this for any postcode entered in cell A30

=IF(LEN(A30)=8,UPPER(A30),IF(AND(LEN(A30)=7,OR(MID(A30,3,1)=" ",MID(A30,4,1)=" ")),UPPER(A30),IF(AND(LEN(A30)=7,MID(A30,3,1)<>" ",MID(A30,4,1)<>" "),UPPER(LEFT(A30,4)&" "&MID(A30,5,LEN(A30))),IF(LEN(A30)=6,UPPER(LEFT(A30,3)&" "&MID(A30,4,LEN(A30))),"??"))))