There will be extremely limited parking on the Saturday due to the Derby County home fixture against Sheffield Wednesday at 3pm.
It may be that you're okay for parking at the Arena if you arrive before 1pm, but unfortunately this cannot be guaranteed. The venue has suggested these options if you cannot get space at the Arena:
Travelodge – 24 hours - £8
Hudson Way Car Park - £5 per visit
Royal Scot Road - £5 per visit
On the Sunday, all cars will be able to park at the venue. If the barriers are down then you will be required to pay £3 for parking.
For some teams (in the morning slots) there is the risk that players will be finishing their day when the Derby game finishes, when there is a obviously a lot of traffic. The venue would suggest that players plan their leaving to avoid the worst of this traffic.