Is there a risk of fire?
Of course there is always a risk of fire, but there are lots of precautions you can take. For instance, you can install heat sensors inside your chimneys and loft spaces, your roof can be sprayed with a fire-proof retardant and you should have your chimneys swept regulary.
Most of these are a must when insuring your roof but others such as the spraying are up to you – but can bring your insurance down considerably.