Chimney fires can be prevented

Keep it clean

Your chimney must be kept clean to prevent fires and structural damage to your property. Clean chimneys also help the environment by assisting the complete combustion of the fuel, reducing emissions in the atmosphere. Regular cleaning of your chimney or flues eliminates the build-up of soot and clears obstructions such as bird and animal nests, leaves and debris.

Standard advice from the Fire Services is: whatever fuel you burn, it’s important to keep the chimney clean and to make sure soot and ash are not allowed to build up. Have your chimney swept at least once a year - more frequently if you burn wood.
Also see Guidance from Hampshire Fire and Rescue: Here

Guidelines for cleaning according to fuel used:

Smokeless fuels should be swept at least once a year.
Bituminous coal should be swept at least once a year.
Wood, every 3 months when in use.
Oil, once a year
Gas, once a year.