I need clarification on why you'd have to work from hom if he takes your DD to school too...but I think I may be able to answer the question without the clarification.
I think that you got used to having a plan and not being able to plan ahead is frustrating for you. Your DH wants to help, but he's not committing or communicating his desire to drive DD to school until after you made plans. Your conflicted because he's trying to do a nice thing (help you), but he's really making it more difficult for you (messing with your carefuly planned schedule). Is it as simple as just sitting down and working out a schedule with him of when he's going to take and when you are? Either he drives her all the time, or you agree ahead of time that he does it three days a week (Mon, Wed, Fri) and you do it two days a week (Tues. Thurs...or whatever works out) and then you can plan your days accordingly. If something changes...like the babysitting thing, then just make it clear "I'm babysitting after work on Wednesday, but I need to go to the office, so I'll go ahead and take DD to school today and bring her home. You can drop her off on Thursday and Friday."