when can i move my lafateria plant and do i need to cut it back

If you mean the woody shrub form of Lavatera, this should be cut down more or less to the base of this year's stems, or where you see new growth sprouting, in late March/early April. If you want to move it, do it now, or by the end of October. If it has a lot of topgrowth, reduce that by up to half, but try to take as little as possible at this time of year - pruning encourages new growth, and that you don't want before the winter starts.