do we by law have to have a service contract in place for the fire alarm system on our premises and is it correct that a service visit has to be done twice annualy.

Article 17 of the the The Regulatory Reform (Fire Safety) Order 2005 states any facilities, equipment and devices provided in respect of the premises under this Order are subject to a suitable system of maintenance and are maintained in an efficient state, in efficient working order and in good repair. This means serviced by a competent person and yes it is it correct that a service visit has to be done twice annually by a competent person and weekly in house also monthly if you have a automatic generator or vented batteries used as a standby power supply for the fire detection and fire alarm system inspected.

Check out http://www.firesafe.org.uk/fire-alarms/ for more information.