The R&C Dining Room and R&C Pub have very different menus. The R&C Pub is simple and limited bar food (fish and chips, chips alone, a cheese and cracker plate, I believe). I don't know if you can order from the Dining Room menu, because I usually just order the "snack size" fish and chips. This appears to be the same size (and price) serving as the fish and chips from the fish and chips stand next door. Much less expensive than the fish and chips in the Dining Room, but a smaller serving as well. Quite tasty, enough for lunch for one or a snack for two. I have done this for lunch in the pub during each of our last two visits to WDW. It has never been difficult to get a table for lunch or a snack, but I've been stopping there in the early afternoon.
Ralph