Plaster to Tile Board transition

[Boolean]

How can I transition between a tiled wall and a base coated\skimmed wall?

The situation is typical I would imagine, tiles on the wall behind the kitchen worktop up to the wall cupboards, then plaster for the remaining distance up to the ceiling.

The existing plaster is all going to have to come off, as its failing in parts and really wonky.

I would like to use tile board\cement board behind the tiles to make it easier to tile and for a little more protection from water from the sink.

I would also like the plaster to be as tight to the block work(coke block) as possible, so as to fit the kitchen units in better, so I was hoping to use 6mm cement board with a thin coat of base coat over the walls.
I'm going to get a plasterer in to skim the walls after I've base coated the block and boarded out.
But how do I transition from the cement board to the base coat?

Is it just a case of mounting the board on the wall, then screed the base coat on the wall above the cement board at the same level? Or maybe slightly less to allow depth to skim?

Should the tile board come slightly higher up the wall than I intend the tiles to come?
Will I need a tile trim to cover the skim at the top tile edge?

Any advice appreciated!

 

[Boolean]

So, I'm down to the coke block on the whole length of wall, which is pretty square and level.

Which should I fix first, the plaster base coat\board or the tile backer?

How do I get the depths levels correct between the two surfaces for tiling(which I will do) and skimming by the plasterer?

The two problems are that the wall runs through to the dinning area which will not be tiled. Only the area just above the worktop will be tiled, so there is also a problem of depth levels where the tile stops and the plaster starts.

There is also a window reveal that will be tiled part way up.

Would I be better off using backer board on the whole wall?
Or plaster board\base coat on the whole wall?

Thanks for any advice on levels and order of operations!
Or anything else!