After Westminster Abbey, you'll be right in the heart of Westminster with a handful of solid lunch options before heading to the pier. Here are a few worth considering.
The Cinnamon Club sits inside the old Westminster Library, just a short walk from the Abbey. It's a well-regarded modern Indian restaurant with a relaxed lunch service — a bit more special than your average midday stop.
Brasserie Blanc on Horseferry Road is another good option nearby. It's a French brasserie from Raymond Blanc with a solid set lunch menu, good for a group, and won't break the bank.
If you'd rather keep it casual and get moving, the Jubilee Cafe inside St. James's Park is a pleasant outdoor spot when the weather cooperates, and it puts you right on the path toward Westminster Pier.
Westminster Pier is about a 5-minute walk from the Abbey, so there's no rush. Plan to finish lunch by 2:15 PM to comfortably board the 2:30 PM boat.