The cost depends on a number of things, not least whether you do at least some of the work yourselves or none at all. More to the point, perhaps, is that it is quite impossible to explain what is involved or how much it might cost without knowing lots of detail about the house in question and its location. The first hint that is needed is whether the house is one or more storeys. As a first indication for your information, the flue would have to be twin walled and insulated and if you choose stainless steel (advisable) then it would not be terribly surprising if the material cost alone came to £1000.or even more. You cannot manage with just a chimney so you would need a stove if you are planning to heat only one room, or if you intend to use a wood burning boiler with your existing central heating system then you are talking about £3000 upwards for the boiler alone. I have a wood burning boiler and it is a true marvel - pumps out heat at around four times the rate we need even in the coldest periods last winter (assuming you would continue feeding it - my fuel is also free), and that is the smallest model from that manufacturer. We maintain 18 degrees minimum 24 hours per day throughout our house (all rooms, halls, stairs and corridors) and raise that to 20 degrees while we are in and awake. Note that all wood burned must be seasoned (2 years minimum) or else you not only spend energy on burning off the moisture but also you get too much tar and other problems with it. Note also that although these things burn very efficiently they are not entirely smokeless at all times, so you need to consider whether you have an intolerant neighbour - it only takes one.