Fireplace discovery!

[Simon and Prema]

Hi folks. We’ve just uncovered this previously blocked up fireplace. This room has suffered from damp (house was empty for 6 months before we bought it). We’ve had it checked and it’s not rising damp but as you can see the fireplace has had a lot of moisture trapped behind some kind of bitumen encased plaster which we removed. 
Questions: can we start to remove the bricks to get the fireplace aired out without fear of it collapsing? 
Should we get supports before we start removing bricks? 
Does the arch serve as a lintel? 
Would really appreciate your thoughts & advice please - we are pretty competent DIYers but don’t want to just dive in without doing some research.

Details- house was built in 1887, this is the dining room and it looks like it was covered up in the 1950’s or thereabouts. 
Obviously once it’s dried out we will get someone in to fix the mortar & brickwork.

Thanks in advance!

[Roundtuit]

Yes, the arch is supporting the brickwork above, and yes, it needs supporting or there's a significant risk of collapse by the looks of it.  Depending on what the plan for it is, you could put a concrete lintel in, but that won't look pretty if you want exposed brickwork.  Also, watch out for a soot-fall; I doubt it was swept before it was blocked up.

[Simon and Prema]

Thank you so much for your reply. Probably plaster over the brickwork and get a fire surround - concrete lintel would be ugly for sure - lots to think about but thank you for your advice, it’s much appreciated 

[Brickie]

You should be fine to remove the infill beneath the arch. Going forward,the chimney stack will need ventilating with an air brick,top & bottom. 

[Simon and Prema]

Thank you for that - we’re definitely going to try to get it functioning eventually too - gracias!