Hack of all your plaster, clean down walls, rake out all your joints, approx 30mm, replace any bad bricks, can scource from reclamation yard, repoint in a 5 sand 1 cement and 1 lime.
Or you can buy tubs of lime putty to repoint.
Best to do all joints then you wont have a difference in colour of the mortar mix.
There are many different jointing methods/finishes , bucket handle most common.
Always looks bad, different coloured joints.
If your bricks are dusty, you can apply some brick sealer.
Bricklayer or good all round tradesmen is what you want.

in my opinion a short bolster and hammer will do the job then you will need a wire brush off any scabs that have been left, for the finish if you want it to look real nice on the finish rake out all the exposed brickwork and weather point with a 3 to 1 ratio mixture sand and cement, a brick y or roofer would do this for you to a good standard,i hope this has been of some help for you.
regards Chris
StayDryRoofers

a bricklayer is who you are looking for.he should be able to hack the plaster off,replace any dodgey bricks and repoint the chimney breast.materials shouldnt cost too much so you are just paying the tradesman for labour.
should be no more than £200 altogether.
hope this helps.

hi a bricklayer or builder like my self would be better for this type of work rather than a plasterer hope this helps

use a chimney liner (flexable pipe thats attaches to the flu of the log burner) this will save the work of knocking off the old plaster an repointing, or knock off all plaster from floor to ceiling and render using 1 cement,1 lime,4 cement mix with waterproofer. any gaps in the pointing will be filled in with the renender which also works as a good key for the scratch coat.

hope this help.