The First Table offer applies to the whole food bill, with the exception of a select few excluded low-margin items if you have opted to add these to your conditions. We try to stay far away from excluding whole sections of the menu as the First Table dining experience is designed to give guests as close to a full-price dining experience as possible - that way they are encouraged to return as full-price paying guests.
In our experience, if you start excluding portions of your menu the diner experience is compromised and guests are less likely to return as full-price customers. We see this reflected in the reviews left by diners where they often comment about items being excluded. It would be a shame to overshadow great reviews so before restricting items have a read of this article on how to get the most out of First Table.