MS Access Reports - Grouping on Calculated Expression field (or even seeing it!)

Where to start...
I have two tables, one refrences the other for values:
Table1: I_TARIFF_KEY
Table2: I_TARIFF_KEY, C_TARIFF_DESC, TARIFF

(C_TARIFF_DESC is mostly numeric, but must be declared as character)

I have an Access query which has both tables in and the following columns:

Col1: I_TARIFF_KEY (Tbl1)
Col2: C_TARIFF_DESC (Tbl2)
Col3: Type: IIf(Val([Tbl2]![TARIFF]) Between 9059 And 9065,"L","M")

Now, usgin these in MS Access is no problem.
Using them in QR2 is impossible!

The TYPE field does not even show up when I link an SQL to the Query?
How can I get this field value as a value for grouping on my QReoprt?
also, is there a way of doing this in Delphi instead of relying on MS
Access (yeuch!)

Basically, I think what I need is a temporary table, or a two pass
method of creating the
'L' 'M' values, and THEN running the report.

Anyone know a quick way of creating temporary tables?
Anyone come across this before.

This is fairly urgent so would appreciate any input soon.
TIA
Robert