Every hire comes with a puncture repair kit, tyre pump, seat adjustment tool, and helmet, however, should require to cycle after sunset, you will also need a set of front and rear lights by law. A high-visibility tabbard may also be advantageous to your safety.
Perhaps you have a lot of ' essential ' items you have to take with you on your cycle tour. In that case you would probably find a front fixing wicker basket, or a rear fixing pannier a necessity.