The only thing you want to put in the table from the lookup table is the ID of the record you select otherwise you will have the same data in two places and that is not good.
If you want to add a person, for example, to a table you would use a combo box bound to the PersonID on a form that is bound to the table. The combo box would be based on the People table and would have their RecordID as the bound column in the combo box. If you use the Wizard to create the combo box it will do the work for you.... To get an idea of what I am talking about open the Northwind database that comes with Access and look at the "Employees" from and the "Reports To" control in particular...
hth,
Jack