Gap Between Ceiling And Wall Tile Shower

Before i put all this together i have a few questions.
Gap between ceiling and wall tile shower. So now there is a varying gap 0 to 1 4 between the top of the tiled wall and the ceiling. I would grout to the ceiling with the same colour as the rest of the walls and as silicone does not paint over i would only recommend decorators caulk. We ve just had a new en suite bathroom done and the tiler has left the gap between the tiles and the ceiling and walls clear. We recently re did the tile above our tub and decided to take it all the way up to the ceiling.
I have purchased some back rod roll to help with caulk fill. The problem is that when we got to the top we ended up with an uneven gap due to some unevenness in the ceiling itself. The gap is fine to fill with grout on either end of the tub but in the middle its upwards of 1 2 3 4. I dont leave any gap at the ceiling unless i cut them short.
I incorrectly tiled my bathroom walls leaving a 3 8 inch gap between the subway tiles and the shower floor tub. Do i need to prepare anything before i install this rod. What would be the correct filler to use to fill in the gap. I asked him if he plans on grouting it and he said that it should be caulked by the decorator.
Anyway the overflow in the loft failed and caused a leak into the bathroom while i was away causing the suspended ceiling to collapse. Hi there in an older house you should be okay to grout up to the ceiling as movement has already occurred within the first few years from when the house has been built however if this is s new build property i would not grout the gap from tile to ceiling as movement will definitely occur so i would use a white mastic sealing but a good quality sealant like mapei mapesil not a cheap. We had to replace the drywall ceiling above the shower which was buckling and wavey. With the shape that we are left with ceilings by plasterers these days i always find it a required practise to cut as accurately as possible to follow the ceiling line.
So with the new plaster board up and the ceramic tiles on we are left with an uneven gap from the last tile to the ceiling. The decorator has just been round to have a look and to provide a quote and he asked why the tiler didn t grout there. On the shower side where we have only tiled half the wall it ranges between 5mm 8mm this is the worst wall the other completely tiled wall looks ok.