You may think that having your boiler serviced is an unnecessary expense, particularly if it's working well. Over time deposits in your boiler build up which not only prevent it from working to it's full capacity but could lead to the production of Carbon Monoxide. Regular servicing will ensure these deposits are removed, leaving your boiler working safely, efficiently and to the manufacturers specifications.
All boilers will suffer wear and tear which may increase the chances of it breaking down. With annual servicing any minor faults will show up and can be fixed relatively cheaply. However, problems that are left too long could lead to a breakdown which may leave you without heating or hot water and could be very costly to repair.
You should also check the terms of your boiler's warranty and your home insurance policy. Most boiler manufacturer's and insurers will require you to have a regular service carried out by a Gas Safe Registered engineer in order for the warranty and policy to remain valid.