Right. In the UK there are certificates for flying competency. In the UK as in the US (and other areas of the world), liability insurance is a requirement in order to fly at organized clubs. The insurance protects you in the event that you damage someone's property with your plane, or worse, hurt someone with it.

Trimming the plane means adjusting the control surfaces while flying so that the plane flys straight and level without control inputs on the transmitter.

Welcome to RCU Jason.
Dennis-