Setting Out Kitchen Tiles: grout thickness for non-matching sizes

It's been a while since my last tiling job. We finished a kitchen renovation some time ago and have been trying to decide since what to use for the splashback. We've settled on tiling (which we had in the pre-renovation kitchen). That decision should come as no surprise to you good folks! (why did it take you so long to come to that obvious decision?!)

We've chosen tiles from Tile Giant. Milan Aqua (the middle tile) and Ice Bar (two variants). All are nominally 200x100. Measuring the samples the Milan is that dimension but the Ice Bar tiles are 198x98. The plan is to do brick bond with random pattern. I would have gone for 3mm grout but that will leave 4mm gaps either side of the shorter tiles. If I stick to 3mm either side of the shorter tile the tiles will get out of alignment unless I have the same number of the narrower tiles on each row. Thoughts?

I have a Sigma 3L cutter. Any advice for cutting the patterned tiles or would my wet cutter be a better bet (last used with a porcelain cutting disc)?

Thanks as always