The whole family is expected to travel to RAF Brize Norton, where the bodies of the three soldiers will arrive at midday.
Two other RMP officers, Warrant Officer Colin Wall, 34, and Corporal Dewi Pritchard, 35, were also killed and a fourth soldier was injured.
The three dead men were in a Nissan vehicle - part of an armed convoy of two vehicles - attacked while travelling from their base through a main street in Basra.