I am about to embark on my first tiling mission. I have 300x600 tiles and 1.2m hardiebackerboards fitted to the bottom half of my bathroom wall. Now I am about to start tiling I have realised that with 3mm spacers for the tiles that is going to add 9mm on which is going to make it slightly higher than the hardiebacker. What is my best way of dealing with this? Trying to trim 9mm from the bottom of the tiles seems like an option but not sure I could do it with my cheap tilecutter. Anyone any suggestions?