Formula for Inventory that calulates an item using different components and tracking of

I have a column in my table named Serves which needs to record serves of says drinks which is easy as that is a straight multiplication of 'Size' by 'Tot Qty"
However when I get to the items "Sausages, Bread, Sauce and Onions" the serves will be controlled by the info in the second table.

Table one will double in size every week and I only want to calculate the formula once so it will continue as the table grows.

Have been trying all sorts of things for two days now and keep running into brick walls.

A copy of the file is attached.

Thanks for your help

Michael

New file attached showing wanted column results

Errors occur because this is an extract of the full workbook

Cheers
Michael

Thanks to both of you - my problem is solved