Flying Fiona,
Let's just stick to facts. Regardless to whether you wish to spend more time with your family or not, I think you are walking a tight rope ! On a legal point of view, you have signed a contract with your employer agreeing to work even unsociable hours. If your personal conditions have changed, I can only recommend a career change, as I do believe it would look better on your CV that you resigned from your job, instead of being dismissed from it for gross misconduct, but obviously, this is your call.
I appreciate where you are coming from with regards to poor working conditions, and I do believe that due to these conditions, a lot of airline staff would report sick for a slight headache, but with all your respect, establishing a pattern like you are doing is a bit foolish as you are only attracting your companies attention.
Just read my previous post regarding your companies rights in this situation, and I wish you luck in getting your priorities right.
All the best to you.