Banding at work

I have recently joined Serco at HMP Dovegate where I am going to be working as a Gym Coordinator. On paper I am contracted as a Prison Custody Officer and as far as I am aware, I will be gaining a separate contract for my role as Gym Coordinator too. Once I have completed my training and graduated as a PCO I will then be working primarily in the prison gym as the gym coordinator (helping to run and over see the gym facilities).

My question is does anyone know what banding I will be under. I ask this question because a Prison Officer is typically a band 3 however, a gym coordinator I would have thought comes under band 4 because it is a specialised area (like a physical education officer does). This role is new to this prison and I am the first person to undertake it, no one at the Prison currently is able to answer this question and I would like to know what banding I would be under or if I would be a combination of Band 3/4 as it is a dual role. Can anybody help me find out?