Rolling uneven turf will make bigger undulations than making it better. You are right though, walking on newly laid turf caused it to be uneven.
Get some planks to walk on, moving them so pressure is not always on the same place.
Using the planks towalk on, roll back the turf or cut it and fill the dips with more soil. Smooth it down, replace the turf and with anothr plank...place the plank on the relaid turf and walk on the plank to compact the soil underneath. This is even pressure and wont cause dips.
Rewater regularly and keep off it for at least 3 weeks. You can use the planks after watering allover the lawn eg stading on one moving the second in front of the first.......long and labouring Im afraid. You will need to water as the turf needs it, specially in very hot dry weather for the first summer.
Good luck