AT EASE is an advice service to those in the armed forces and family members which has been running since the 1980s. It is staffed by volunteers. There is a telephone helpline or you can send an email. There is information on various terms of service issues and conscientious objection on the website.
New legislation (from 22 July 2011) which grants under 18s the right to leave after a 'cooling off' period. Prior to this, discharge of 'unhappy minors' was at the discretion of the commanding officer.
Information on registering a conscientious objection in the UK armed forces.