Insomnia is a common problem after hysterectomy. If you've only been on HRT for that year or so after surgery, you may have a hard time finding a doctor who will prescribe it. The fact that you smoke may also be an issue although a transdermal form (e.g., a patch) would be safer than oral (less risk of clots). Also, it can be hard to treat insomnia that has been going on this many years. But it may be worth a try. I hope you find something that works!
Talk it all over with the doctor. It doesn't sound like you have a lot of choice, if taking hormones will help this. They don't need to be shots, for heaven's sake.
If you do go to HRT, it might even give you some incentive to quit smoking, which would be hella better for your health.