Most of the Tambour Doors I have seen are usually made of oak. A hard wood is needed because of so much use in the movement of the product. To build a roll-top of solid oak is going to be very expensive. I suggest that you use a veneer wood to make the large panels & suggest pine for all the drawer inserts. Make sure that you get the best quality drawer tracks that you can afford. This is the most important part of any desk. Good luck with the project!
An after-thought! Also, you may want to check with a few local cabinet shops in your area to see if they would consider selling you the veneer panels. I have seen some cabinet shops actually do this & they buy only the best wood, if they are a reputable builder. Most lumber yards don't carry good quality wood like you would use to build a fine piece of furniture.