Adult Off-Peak Day return is £15 per adult from Brum to Nottingham with Cross Country Trains. (The train originates in Cardiff and calls at Tamworth, Burton and Derby en route) I've booked mine but seat reservations were not an option - there'll be a seat for me somewhere. I have Gill's and Soupy's mobile number. Anyone else travelling through Birmingham just drop me a PM if you want to contact me on the day.
For info: Off peak means leaving Birmingham from 9.30 onwards, return any time after 6.30pm.