Arriva Trains Wales and TransPennine Express are listed as accepting XC tickets on 19th November, they will therefore probably accept them on 25th too - you can check back closer to the time.
However, XC if it's the same as this weekend they will be running trains from Cheltenham Spa towards Leeds. It seems likely that with the reduced service they will by 8/9/10 car formations so you will probably still be fine doing that. The only potential problem with this would be the limited ATW service from Cardiff Central to Cheltenham Spa: 1030, 1224, 1425, 1625 and 1824.
I assume that your tickets are something like Ikley to Leeds CDS and then Leeds to Chesterfield, Chesterfield to Birmingham Stations, Birmingham Stations to Cheltenham Spa and Cheletenham Spa to Cardiff Central Advnaces?