Cymro is on the right lines, simply its upto an F or X however as you will see we got a mix bag. At present I have a T6 which is Prestige on a C group, most would be very unlikely to get that. I have had it in the past where I booked a G and got a H as they said PC but I think they were short on cars.
I would say book a C for manual and expect anything from a D to a X group. if you want a Auto book an E and expect normally a F group.
Reminds me I need to swap later today, the XC70 is costing me a fair bit on local roads, think i am going for a V40 Auto F group and keep it for a few months or it has a problem