Spoiled child

OK so here it is. I'm a 44 year old father with a 6 year old daughter. The problem is that I have always spoiled my child and tried to give her everything I could possibly supply in order to give her as many opportunities as possible in life and grow her natural intelligence. I also have spent many hours playing and have become her best friend. Now I recently decided to go back to school full time and I also work full time. The problem is she is not willing to allow me to do my school work. She cries and throws tantrums in hopes to get me to play with her. I have tried finding other interests for her like painting and drawing and have also tried involving her in my school work. Nothing works. She always jumps in my lap and asks me to play and its becoming a nussence to me and also creating feelings of resentment. Any advice would be well taken along with criticism as I know I created this problem but am up to try almost anything in hopes to teach her and myself how to separate a little better. There are many other factors in my home life that may have some to do with this and I will happily answer any further questions as fast as possible. Thank you anyone for your help. Sincerely,Geoffrey