Opening up chimney, safe?

[RedMango]

Hello all, started to remove/open up the chimney breast in this 1930s house for a hob top.

 

Breast is 1545mm wide

Lintel is 1200mm wide

The ends of the lintel sit on 150mm of brick

 

This is the first time so unsure on a few things;

1. The brick work inside the chimney is only sporadically tied into the front wall with bricks going side ways. Do I need to support the inside section with anything or is it another being tied into the front facing wall?

 

2. Most annoyingly the brick pictured on the right hand side has come loose and the brick below hasn't broken off cleanly so I'm concerned the overall support for the lintel is no longer enough? How could I rectify this?

 

Any other points you notice please let me know.

 

Many thanks