Stoves can be easily self-installed but you need building control approval (which is easily done). You may wish to have your stove installed by a Hetas registered installer in which case you do not need building control approval. more information on stove installation.
Rockwool insulation sleeves for use on chimney liners. The sleeve is pushed down over the liner as you put it down the chimney. There is a self adhesive tape that holds the sleevs together. Another option is to put the rockwool sleeves on the liner and then pull the liner up the chimney. If you use this method you have to somehow secure the sleevs so they do not fall off the liner.