If you own a thatched dewelling then contact your insurance company today to clarify what their requirements are for frequency of chimney sweeping and the use of spark guards. Many now insist on spark guards being removed. Sweepover will provide a certificate to show that the chimney has been swept by an appropriately qualified chimney sweep.
If you are thinking of having a stove fitted then get it done by a HETAS qulified installer. Have a look at the two attached PDF documents at the bottom of the page first.