Is your new flat on the ground floor? Over a basement? Over neighbors? If it's one of the first two, the floor can be strengthened using pillar blocks, vertical 4x4 posts, and crossbeams. The crossbeams are placed under the part of the floor where the tank will sit in a perpendicular arrangement to the existing beams. The crossbeams are braced with the posts, and the posts sit on wide-foot pillar blocks (adjustable pillar blocks are used so you can use a spanner to cinch the adjustment nut to get a nice tight fit without needing to use wood wedges.
If your flat will be over another flat, then the only safe way to run a tank this size will be to situate it perpendicular to the direction of the existing floor crossbeams. That way, more support structures are being used to hold the tank. Also place the tank at a load-bearing wall as these are the strongest points of your floor.