Spent a few days digging my back garden over now need a roller to compact the soil before i plant grass seeds preferably a water filled one because i will have to pick it up in my car. Thanks all

Hi I am not a gardener but have successfully laid a number of lawns, you do not roll the soil before sowing seed.
Rotavate and then rake out use planks to walk on soil.
Compacting the soil can lead to drainage problems good luck