If you can get the slots, you could try booking one each Saturday and one each Sunday. You'll only fly half of them, as you have observed, but you'll still get in the average one lesson per week ... and you'll get most value out of the Sunday lessons where you have managed to fly the day before.
Oh, and about the self employed bit ... I thought one of the main points of being self employed was being able to take time off work whenever you feel like it! - that's why I do it, anyway.