Booking: Always book in advance: there are often better prices than on the door, plus you walk straight in. (You can leave and go back in- get a wristband on leaving)
ExCel: Central "Mall" has loads of fast food outlets, gets predictably busy at midday. Several speciallist food places, and a couple of "Railway Station" sandwich & drinks places. Toilet facilities at intervals along the mall, generally very clean.
You can leave coats etc in downstairs cloakroom. £!:00 per item. (The show is quite warm, heavy clothing spoils the day)
The show itself is a big showcase for boating related interests; from multimillion pound powerboats to rowing dinghies, and a lot of equipment manufacturers, and general chandlery stands. Mainly enthusiastic men with less enthusiastic women in tow. A great day out for the sailor; knowlegable experts in all areas. The "Tullett Prebon Boat Show" website has full details.