Tiling advice

I would welcome any advice on tiling an unusual interior area. It is a spilt level area. There is an existing slab with a core fill block wall step down (I course only) bordering the slab. The top of the block is the exact same height as the slab. I want to tile across the slab and right up to the end of the block. My dilemma is there is a 100mm gap between the block wall and the border of the slab. I am happy to fill the gap with 100mm of concrete to make one continuos level. However do you think I can then lay tiles over the concrete filled gap and to the edge of the block wall with out them cracking along the joints in the future?

2 ideas - very hard sight unseen. Movement (obviously) is the biggest problem, so get rid of the problem - cut the blocks down to lower floor level and only tile as far as slab? Or have a seperate band of tiles along top of blocks and use a flexible filler to slab tiles

Thanks for the reply Andrew patrol. I think the band of tiles might be the go.