Just spoke to him, it looks like my dad is the one who supplied him with the wickes grout - so the builder isn't to blame for that one.
He says the reason for the uneven foor tiles is possibly due to the difference of the floor on both sides of the kitchen (1 half is wooden floor boards and the other half is concrete from an extension carried out years ago). He believes the temperature difference due to the wood ply on the concrete floor being much colder/damper may be a reason as to why the tiles are not level. He says he will be sorting out those tiles that are uneven.
As for the cracks in grouting, he said its expected and due to the grouting not fully sinking in. He says after another layer of grouting, it should be ok.
He says he is yet to put the strip thing on the wall tiles and he will be sorting out the one which was sticking out in the photos. Same with the one where the grout has gone over a white tile. Some of the other tiles sticking out on that side of the wall are due to some pipe work on the original wall so it would never be a 100% straight finish. He seems to acknowledge all of these things and looking to rectify. Will keep you updated and thanks for everyones input.