As a heart attack survivor, it is even more important to talk with your doctor before I would recommend you do any exercise at all. While I understand your need to get healthy, you really need to get medical clearance. Recovery heart rate (how quickly your heart rate recovers after exercise, is an indicator of heart health. As to what that drop should be, as a heart attack survivor it may be different than someone who is healthy.
Your state or county health department, as well as social workers at your local hospital, can also provide information about free health resources in your area. The website linked below can help you find free or low-cost medical care in your area. findahealthcenter.hrsa.gov/Search_HCC.aspx