Cleaning your chimney or flue on a regular basis is important as it will prevent a build-up of soot in the chimney.
The frequency will depend on a number of factors including how often the stove is used, the moisture content of the wood used and the type of chimney.
At the very least the chimney should be swept at the start of the heating season. The Guild of Master Sweeps recommends that the chimney be swept quarterly during the period when the stove is lit.
It is recommended that you engage a trained chimney sweep to clean your chimney.
A chimney is designed to safely transmit the products of combustion to the atmosphere. If you are at all concerned about the integrity of your chimney you should seek professional advice right away and have it repaired by a competent person.