The Gas Safe Register (formerly CORGI) recommends that any gas appliances, including boilers, are serviced at least once a year.
By getting your boiler serviced every year, you are ensuring it is kept working efficiently and reduces the risk of an untimely and possibly expensive breakdown.
You can get a regular boiler service contract and boiler / central heating system insurance to cover breakdowns. These provide piece of mind and gets any problem seen to quickly.