there is an awful lot of masonry above your floor which depends on your section for support,Not safe to remove without strucural survey and adequate alternative support being provided
When we bought our first house one of the chimneys had been removed in the kitchen and bathroom but was still standing, unsupported apart from the bathroom ceiling in the attic and on the roof! Talk about dangerous! We obvioiusly had to get the rest of it removed, getting a contractor to remove the bit outside and then taking it down in the attic ourselves. When we'd taken it all out the bathroom ceiling collapsed, thank goodness it didn't do it whilst there was still chimney on top of it!
Thanks everyone ... wouldn't have even been considering it except at the suggestion of our our builder & brickwork specialist of 40yrs experience, who is well known locally for excellent reputation, so I doubt he'd do anything daft. We are about to take out the fireplace & his opinion is that the whole thing might as well go. But, frankly, I've seen enough brick dust!!!