Hi Margaret and welcome to the community.
It's ok to listen to lifeflow while you're doing other things. As you say, it's not the optimal way to listen to it, but you'll still receive some benefits.
Do you practice meditation yet? If not, download the free "Discover Meditation" cd's and listen to those as that is really the building block upon which all the other stuff sits better.
The good thing with signing up to Lifeflow is that the support team are really helpful. If you want to stop at any point you can (there's no tie ins) and you can resume again later, or you can ask to have it delivered less frequently if that suits you better. They're very amenable.
Look forward to seeing you around on the forums.
Hugs
Giles