Couple of points.
1. That's the structural fireplace opening you've exposed, not the fireplace as it would ever have appeared at any stage in the house's history.
2. I assume you have listed building consent for the work you are carrying out?
Is that the kitchen? Is that the space where the Aga (or such device) used to be, and are those the heating pipes that ran from it? It certainly looks interesting. As to what you can do with it...
As others have said, the first thing to do, before you get too deep or do too much "installing" is to get the Conservation Officer to come and look. Discuss what you are thinking of doing. As an ally the CO can be a great help, offering ideas you'd never have thought of. As an enemy, you are in trouble.
We had lots of ideas for this house. Only one really mattered, and the CO guided us in the right direction on that. He was also extremely helpful with the planning and execution of a major restoration project that used up a large slice of our savings. We have no regrets!
That looks like a back boiler from an open fire to me. We found something similar behind one of our fireplaces.
I would also echo the above two comments regarding CO-approval for such alterations, especially given the previously described history of unauthorised alterations because of the unknown listing status.
This is the orginally Chimney as it once was, as the two Cottage as they are now were once 4 up and downs. In addition to this the neighbour has kindly shown their chimney which is almost identical , also many pictures dating back atleast 150 years. The 'Structual fireplace opening' as mentioned was filled with alot of loose rubble and bricks which were not supporting anthing above them. I will try and upload a picture later this evening when I am home showing up the fireplace which is some view.
Yes we have been working with the local CO officer who has also visited the property and provided alot of useful information and ideas. Like ourselves he was frustrated as to why the previous owner(s) have plastered over just about all the remaining orginal features - which is not many as most have been ripped out and replaced.
In the fireplace was found the Old back boilder and we plan to replace with a clearview Log Burner:
http://www.clearviewstoves.com/vision500.htm
The picture of this Chimney is in the lounge, through the other side is the Kitchen/dinning room which has a very similar opening chimney.