Always in a rush

How much of my day am I supposed to spend with my children, actually educating them?
Last night, I committed myself to one more thing this week, something I really beilve needs to be done; at first it sounded small but will actually will involve my children spending most of the afternoon with a kind friend.
I am teaching an antenatal class one evening and, because I am busy in the late afternoon, I will have to spend some of my early afternoon preparing and so my children will not get the benefits of my full attention.
I have a personal appointment another afternoon, so they will spend some more time with a different friend although I am intending on taking natural history DVD for them to watch so it will be "educational" and not too much trouble for my friend.
I have planned to take them swimming and shoe shopping. My eldest has two deadlines this week, one for a competition and one for an e-mail book club he belongs to, and a maths test. My little girl is taking part in a CBeebies Christmas Special and needs taking to the studio and collecting.
As I try to work out how I'm going to fit all this in, along with keeping the house clean, the children dressed in clean clothes and the family fed, I start knocking things off the list of what we're going to do. So, I don't have to go swimming, they don't need shoes this week; I don't need to have a quiet evening to knit the four hats I've promised for the church fair in less than two weeks.
With the aid of a couple of kids' DVDs I could free up some time to get everything done, but what about the children? What do they actually need? I'm trying to be imaginative and creative about the time I am with them. I've just got some audio books on CD so I can make the car journeys more profitable, I can read chapter books at bedtime instead of the day, we can combine shoe shopping with a poetry tea in a cafe.
I hear myself too often tell the children that I'm in a rush, or that I have so much to do. I have sent the children away more than once even while writing this. I'm not sure what yet, but something this week is going to have to give!