formula involving VLOOKUP and IF ACCOUNTS PAYABLE 30 and 60 day based on consultant terms

I am trying to work on formula involving VLOOKUP and IF

On the accounts payable worksheet I am trying to automatically update the due date based on the payment terms in column F. How do I do this? Are there other formulas to use? Need Help.

The cells in payment terms columns are automatically updated when the drop down column E is populated with a consultant. The consultant array is CONSULTANTDATA in worksheet Consultant. The payment terms are assigned in this sheet as well (column M) drop down menu where cell information is derived from array PAYTERMS under the Terms worksheet.

This is the formula I have been working on but need some help.

=IF(VLOOKUP($F2,PAYTERMS,1),$B2+VLOOKUP($F2,PAYTERMS,1))

Thanks is advance!