skim coat vs cement plaster


New Member
Hi everyone.

I have to make decision how we are going to finish our internal wall and after spoke with few builders and reading internet and youtube I just grow stupid and so confused.
Some walls are plasterboards, new partition wall made from Quinnlite thermal blocks, and some walls with old render.

I found out that I have following options:
1. Skim coat
2. K Rend cement based render
3. Sand cement lime - scratch coat, base coat, top coat.

My dilemma are:

- what would be the best choice in terms of the health environment in the house and walls.
- one builder said that skim coat is not breathable and not good, is that true ?
- in the future I will have to add new stud wall to the existing, and builder said if I skim there will be always cracked, is that true ?
- on the thermal blocks is applied one coat of thristle bond what would be the best way to finish this.

I will be much appreciate for any advice because I am stacked for good with this.