Opening up a chimney for a stove

[Gaz73]

Hi got a question about how to go about making the recess bigger to fit a stove? got a few quotes today for the stove and fitting but the opening behind our fire is too small so will need knocking out which I can do myself but a bit worried about what I can knock out ? the fire opening is offset to the wall which doesn't help

?

 

[vinn]

There's plenty of recent threads & lots of advice on recent threads about this very subject.
Why not search for them in the search box?

Briefly, you should only open up when you have the installation dimensions for your new appliance.
You open up, and possibly lintel, to those dimensions not just any willy nilly opening.

Pics showing the whole c/breast & the hearth area would help.