To Alam after the damp problem has been sorted out you can render and skim the wall, make sure you use

Comment posted to Learning to Plaster by Plastering and Struggling with Drywall by Phil.

To Alam
after the damp problem has been sorted out you can render and skim the wall, make sure you use a waterproofer in the render and leave a gap about 2cm from the floor to let the bricks breath, you won’t see it if there is skirting board covering it.
scratch the render and the next day skim.
To John
If you stop part way through a job and come back to it you will see the join, even if you feather it really well, you have to plan to do the complete surface as one job, if you are patching then the best you can do is feather the skim but as I said if you are painting over it you possibly will see the join unfortunatley.
To Asa
that is a big ceiling (56m2), when I do commercial buildings with long corridoors and big office ceilings I always have at least one other man with me, however, most office ceilings are suspended now so I don’t do many. I have recently done some restoration work in a listed building which meant working with lime and horsehair over lath, it was actually OK to work with once we got the mix right.

A word of warning, plastering is VERY hard work, especially cielings. And there is nothing more anoying than spending a day grafting to find the finish is not as good as you would have hoped, knowing what I know, I would probably pay a plasterer to come in and do the job right first time (well I would say that wouldn’t I ?)