how to prep this wall for tiling

[cal_blam]

I took off old tiling and underneath were these loose little square concrete blocks mounted on the brickwork. You can see there are four little circles on each block which stick a few mm out. Which I can grind over, but the whole surface will still not be completely smooth.

Some of the blocks were loose and came off, so I have done some rendering in concrete (thats the darker patches).

Now I will be retiling the original tiled area, and also tiling a bit higher and wider,over the original painted plaster areas.

Basically wondering what is the best way to prep/smooth this area, while minimising how far proud the tiles will sit out from the wall. A layer of board would be too thick. What about maybe grinding off the rough bits and effectively rendering smooth and drying first a layer of plaster or tile adhesive?

I'm understanding from some reading here that I can't just use a single really thick layer tile adhesive to set my tiles - will end up with uneven tiles? (edit: tiles will be 100x100)

lhttp://www.renovateforum.com/attachments/f209/90468-how-prep-wall-tiling-imag0006.jpg

http://www.renovateforum.com/attachments/f209/90469-how-prep-wall-tiling-imag0005.jpg

[heavytrevy]

Grind and render till the surface is within spec's , 2 metre straight edge across the surface with no more than 5 mm variance (hump or hollow )

[cal_blam]

Grind and render till the surface is within spec's , 2 metre straight edge across the surface with no more than 5 mm variance (hump or hollow )

Thanks...I don't think it is too far off that spec with some grind and render. Wondering what is the easiest sort of render I can work with to go over the existing - I think what I used for the first rough patchup was have a bag of pre mixed sand n cement. I find I want to make it runnier to make easier to smooth, but then it doesn't stay in place.

Is there anything easier to work with or do I just need to learn how to use concrete better?
Can I just grind back the concrete a bit and skim over a thin layer of plaster? That might be easier than working with concrete.