If you hear dripping or a gurgling sound in the pipework or your radiators, it likely means air is trapped in the boiler system. You never want to have air in your boiler. Trapped air prevents heat from radiating sufficiently throughout your rooms. This causes the boiler system to run for longer periods and use excessive amounts of fuel to heat your home. Also, be sure to regularly bleed your radiators or do so when you hear odd noises to ensure you are getting maximum energy efficiency from your boiler heating system.
Another possibility to be aware of that can cause gurgling is if you have a frozen condensate pipe. If one of the pipes has frozen, immediately defrost the pipe to avoid damage to your boiler. First, you will want to locate the frozen blockage and defrost it by pouring hot, not boiling water on the pipe to thaw it. Alternatively you could use microwave heat pack, hot water bottle, or a hot towel to thaw the pip out.