Excel 2002 VLOOKUP help

Wonder if anyone can help me with this please.
I'm using this formula in Excel 2002 and it works OK.

=VLOOKUP(B5,'J:\Lee\House\Cabling Records\Master Cabling Record.xls'!FFWW2,2,FALSE)

I need a way of automatically changing the "FFWW2" part of the table array, by inserting the contents of a cell from the current sheet.

E.g. cell M12 has a label "From", the contents of which, change. I want the contents of "From" to be automatically inserted to replace "FFWW2"

I've tried putting the cell name in place of "FFWW2", putting another formula enclosed in quote marks which points to the contents of "From", putting the actual sheet name & cell name in the formula. Nothing works.

Is there a way of doing this?

Any help with this may just prevent the loss of the last bit of hair I have!!

Many thanks.

Lee