It is sad, huh? I hated it too!
Good news is that she will LOVE it!
Changing visiting time with The Grans to the times you have class sounds like a reasonable suggestion to me. Win-win-win all the way around! I am sure the grandparents will understand, especially if you are honest with them and just tell them your feelings...that you are going to miss her and will want as much time with her as possible and ask if they watch/visit with her while you are at your class and how that would really help you out.
My daughter is almost 5 (in 10 days!) and in her 2nd year of preschool. Her first year was 2x a week/2.5 hours/day (5 hours total) and now that she is in her second year it is 3x a week/2.5 hours/day (7.5 hours total)...I know that doesn't sound like very much time to most, especially those who have to have their kids in daycare while they work but it was/is a HUGE chunk of time to me and it hurts to see them go and grow even though I/we know that it is SO good for them and that we want them to learn and grow!
Just last week my daughter was saying how she is SO excited to start K so that she can go to school every day! It makes me want to cry just thinking about it. She is my baby, my 3rd and last child......and they just grow up WAY too quickly, darn it!
***Kellie B. is NOT alone...I too hate September! I hate sending the kids back to school...I absolutely LOVE having them home with me during the summer and on winter and spring vacation!