I think you should talk to your doctor about a diet and exercise plan that is tailored to suit your needs. They may also have you see a nutritionist to figure out the right diet for you. I think it would be best for you to check with the doctor before you start a diet plan, since you need to make sure you are healthy enough to exercise and that the plan is right as far as nutrition.
My brother-in-law did have gastric bypass, but it isn't the "quick fix" many think it is. It is painful and there can be complications from it. He is now very happy with the way he looks, but has had some major health ups and downs throughout the process. The doctor can help you decide what is best for you, and discuss surgical and non-surgical options.
Please don't let the lack of health insurance stand in your way. You could ask your doctor if there are any organizations/programs that would help you with the cost of medial bills while you lose weight. Hospitals also have social workers who can help you with your bills and put you in touch with organizations that can help you pay. Also, contact your local charities like the Lions Club, local churches, etc. See if you qualify for any government programs, like Medicaid. Are there any health clinics for the uninsured in your area? Look for them online or in the newspaper. Often you can go to a clinic for the uninsured and they can give you referrals to see specialists and they can help you find a financial adviser/social worker to talk to about the bills.
Good for you for taking steps to get your good health back!

This a great place to come for support. Also, ask your doctor about weight loss support groups in your area. They can be a huge help in losing weight and keeping it off.